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ELEMENTARY 
AND  DENTAL 
RADIOGRAPHY 

BY 

HOWARD  RILEY  RAPER,  D.D.S. 

Professor    or   Roentgenology,    Operative    Teclinic,    Materia 

Meaica  and  Xnerapeutics  at  tte  Indiana  Dental  College, 

Inaianapous.     Past  Dental  Surgeon  to  tke  Indiana  Sctool 

for  tLe  Feeble-Minded  Youtk.      Member  American 

Institute  or  Dental  Teacners,  local,  state  and  national 

dental  societies.  First  District  Dental  Society  of 

tne  State  of  New  York,  ^iVestern  Roentgen 

Ray  Society,  Associate  Fellow  A.  M.  A., 

Section     of     Stomatology. 


WITH  OVER  500  ILLUSTRATIONS 

SECOND  EDITION 


Adopted  as  a  Test-Book  by  the  National  Association  of  Dental  Faculties 


NEW  YORK; 

Consolidated  Dental  Mfg.  Co. 

LONDON : 

Claudius  Ash,  Sons  &'  Co.,  Ltd. 


^7'  ^"Z-l  t^ 


Copyright,  1913 

By  HOWARD  R.  RAPER 

First  Reprint 

May  17,  1916 

Second  Reprint 

July  5,  1916 

Copyright,  1918 

By  HOWARD  R.  RAPER 


Copyright,  1913,  in  the  United  Kingdom 
By  CLAUDIUS  ASH,   SONS  &   CO.,  LTD.,  LONDON 


One  of  "his  boys,     the  -writer, 

grasps  this  opportunity  to   sno-v^ 

nis  love  ana  respect  for 

GEORGE  EDWIN  HUNT, 
M.D.,  D.D.S. 

ty  aedicating  tnis  book  to  bim. 


PREFACE 

FIRST  EDITION 

The  object  of  this  book  is  to  teach,  first,  the  elementary 
principles  of  radiography ;  second,  special  dental  radiography. 

The  first  part  of  the  book  is  written  on  the  presumption  that 
the  reader  knows  nothing  about  electricity,  photography,  or 
the  X-fays,  and  might  therefore  be  used  by  anyone  zvho  wishes 
to  take  up  radiographic  work,  whether  a  dentist  or  a  physician. 
In  dealing  with  the  preliminary  subjects  mentioned,  an  earnest 
effort  has  been  made  to  avoid  useless,  impractical  and  confus- 
ing elaboration. 

The  second  part  of  the  book  is  devoted  to  dental  radiog- 
raphy, and  is  consequently  of  interest  mainly  to  dentists  and 
specialists  in  radiography  who  do  work  referred  to  them  by 
dentists.  It  gives  in  detail  the  special  technic  involved  in  the 
practice  of  dental  radiography,  also  a  chapter  with  one  hun- 
dred and  eighty-three  halftone  illustrations,  demonstrating 
sixty-four  different  uses  to  which  the  radiography  may  be  put 
in  the  practice  of  dentistry. 

The  use  of  the  radiograph  in  the  practice  of  modern  dentistry 
is  not  a  mere  fad;  it  is  a  necessity,  if  one  wishes  to  render  the 
best  dental  service.  Nothing  but  great  good  can  come  from  its 
more  frequent  use.  To  the  end  of  bringing  about  a  more 
extensive  use  of  the  radiograph  by  dentists  this  work  is  pub- 
lished. At  present  it  is  the  only  work  of  its  kind  on  the  book 
market. 

So  many  people  have  helped  me  in  the  compilation  of 
this  volume  that  I  refrain  from,  naming  and  thanking  any 
particular  individual.  A  publication  of  this  kind,  of  necessity, 
represents  the  work  of  many. 

H.  R.  R. 


PREFACE 

SECOND  EDITION 
{The  beginner  in   radiographic   work   should  read   this.) 

As  stated  in  the  preface  of  the  first  edition  "  the  object  of  this  book  is  to  teach, 
first,  the  elementary  principles  of  radiography;  second,  special  dental  radiography." 

When  the  beginner  sees  this  book,  for  the  first  time,  and  notes  its  size  I  can 
readily  understand  the  feeling  of  discouragement  which  would  induce  him,  to  offer 
a  prayer  for  a  smaller  book — one  which  treats  the  subject  in  a  less  exhaustive 
manner,  more  in  the  manner  in  which  the  average  man  wishes  to  take  it  up.  The 
prospect  of  having  to  "  wade  through  "  thousands  upon  thousands  of  words  to  gain 
a  comparatively  few  practical  facts  is  certainly  not  an  inviting  one.  So  allow  me  to 
direct  the  alarmed  beginner's  attention  to  these  facts:  The  Place  to  begin  study 
is  at  the  beginning  of  the  book — not  the  middle.  The  entire  subject  of  Electricity 
is  covered  in  only  13  pages!  The  subject  of  Elementary  Radiography,  including  the 
12  pages  devoted  to  Electricity,  and  chapters  on  X-ray  Machines,  X-ray  tubes  and 
the  X-rays,  and  the  technic  of  Making  Radiographs  is  covered  in  84  pages.  Only 
52  pages  cover  a  detailed  consideration  of  dental  radiographic  technic.  Thus  the 
entire  subject  of  Elementary  and  Dental  Radiography,  as  most  men  will  wish  to 
take  it  up,  is  covered  in  only  145  consecutive  pages.  From  page  145  on,  com- 
mencing with  the  chapter  on  "  The  Uses  of  the  Radiograph  in  Dentistry  "  the  book 
becomes  a  reference  book,  special  attention  having  been  given  to  the  index  in  the 
back  of  the  book  so  the  reader  may  locate  the  subject  he  wishes  to  "  look  up  "  with 
ease. 

Much  of  the  first  edition  of  this  book,  particularly  the  elementary  part  of  it, 
was  written  from  old  notes  which  I  had  made  for  my  own  benefit  at  the  time  I  was 
engaged  in  educating  myself  in  radiography.  It  is  owing  to  this  fact  more  than  any 
other  one  thing,  I  believe,  that  the  book  has  proved  of  such  definite  value  to  be- 
ginners in  this  work;  the  tone  of  the  text  is  not  beyond  the  comprehension  of  the 
man  or  woman  who  is  just  taking  up  the  work.  It  is  with  this  in  mind  that  I  have 
refrained  from  altering  the  original  text  as  far  as  possible,  in  this  the  second  edi- 
tion, and  have  written  an  appendix  to  each  chapter  where  necessary,  giving  therein 
such  further  consideration  of  the  subject  as  changes,  which  have  developed  in  the 
past  few  years,  seem  to  demand.  In  this  way  I  hope  to  avoid  the  mistake,  most  com- 
mon with  writers  on  electro-dental  and  medical  subjects,  of  overloading  the  reader's 
mind  with  details  at  the  outset. 

Though  I  have  followed  the  plan  of  revision  just  outlined  as  far  as  possible, 
I  have  nevertheless  found  it  imperative  to  make  a  number  of  changes  through  the 
look  and  to  rewrite  Chapters  V  and  IX.  These  changes  I  hope,  and  believe,  will 
add  to  simplicity  rather  than  detract  from  it,  and  the  appendix  may  be  read  by  those 
who  have  prepared  themselves  for  it  and  feel  the  need  of  further  knowledge  on  the 
subject, 

I  made  the  statement  in  the  preface  for  the  first  edition  that  "  the  use  of  the 
radiograph  in  the  practice  of  modern  'dentistry  is  not  a  mere  fad;  it  is  a  necessity, 
if  one  wishes  to  render  the  best  dental  service."  Let  me  concede  that,  as  some  men 
use  it  to-day,  the  use  of  the  radiograph  in  dentistry  is  only  a  fad. 


New  methods  and  things  introduced  into  medicine  and  dentistry  are  often  re- 
ceived -with  over  and  irrational  enthusiasm,  followed  with  their  equally  irrational 
abandonment.  The  extensive  use  of  the  radiograph  is  new.  It  is  just  about  to  pass 
through  the  stage  of  reaction  from  over-enthusiasm.  Its  use  will  never  be  aban- 
doned, however;  so  let  those  of  us  who  know  its  limitations  teach  those  who  do  not 
know,  lest  in  their  discouragement  and  misunderstanding  they  fail,  for  a  while,  to 
avail  themselves  of  this  necessity  to  service.  Accordingly  the  Appendix  to  Chapter 
VI  has  been  written,  which,  to  the  very  superficial  thinker,  will  seem  a  tirade  against 
the  use  of  the  dental  radiograph,  but  which  in  reality  is  a  most  pertinent  recogmtion 
of  the  fact  that  we  will  always  use  dental  radiographs. 

The  use  of  dental  radiographs,  coupled  with  the  modern  theories  of  metastatic 
infection  as  a  cause  of  so  many  different  diseases,  brings  the  old,  old  problem  of 
pulp  canal  work  before  the  dental  profession  in  a  new  light — the  light  of  the  X- 
rays  and  holds  it  there  demanding  a  solution.  It  is  fitting  that  we  should  consider, 
at  some  length,  "  The  Problem  of  Pulp  Canal  Surgery"  in  this  volume  and  accord- 
ingly a  chapter  on  this  subject  will  be  found  in  the  appendix.  The  X-rays  have' 
played  a  most  important  part  in  bringing  this  problem  before  us  again  and  they  will 
play  an  equally  important  part  in  its  solution.  I  direct  particular  attention  to  the 
chapter  on  "  The  Problem  of  Pulp  Canal  Surgery  and  Oral  Infection,"  believing  it 
contains  material  of  considerable  i)nportance  to  the  dental  profession,  the  medical 
profession  and  last,  but  far  from  least,  the  public. 

By  way  of  explanation  in  fairness  to  some  of  the  men  whose  names  appear 
beneath  the  radiographs  in  Chapter  VII,  and  in  fairness  to  myself  as  well,  I  wish 
it  known  that  the  radiographs  illustrating  this  chapter  were  chosen  primarily  for 
their  clinical  value,  and  not  because  they  are  examples  of  excellency  in  radiodontic 
work.  There  are  183  radiographic  illustrations;  m,ost  of  these  are  excellent,  many 
are  ordinary,  and  a  few  are  poor,  but  of  such  definite  clinical  value  that  it  would  be 
a  sacrifice  not  to  use  them. 

The  policy  of  not  retouching  radiographs  has  been  adhered  to  very  closely, 
for  retouching  takes  the  "life"  and  "personality"  out  of  radiographs.  Only  a 
very  few  radiographs  have  been  retouched. 

In  this  edition  of  the  book,  as  in  the  first,  I  have  not  used  the  Roentgen  words 
because  I  do  not  like  them.  Take,  for  example,  the  word  radiodontia:  The  equiva- 
lent for  radiodontia,  using  the  Roentgen  nomenclature  would  be  Roentgenodontia. 
The  literal  meaning  of  Roentgenodontia,  as  my  good  friend.  Dr.  Ottolengui,  points 
out,  would  be  "Professor  Roentgen's  teeth." 

In  compiling  material  for  this  second  edition  I  have  been  impressed  again  with 
the  fact  that  a  volume  of  this  kind  represents  as  much  the  work  of  his  friends  as 
the  work  of  the  author.  I  will,  however,  express  my  appreciation  of  the  co- 
operation of  my  publishers,  whose  liberal  policy  of  allowing  me  to  use  illustrations 
as  freely  as  desired,  regardless  of  expense,  has  added  greatly  to  the  teaching  value 
of  the  book.  Also,  I  must;  I  cannot  keep  from  thanking  Dr.  lohn  Callahan  and 
Dr.  Dave  House,  and  my  secretary.  Miss  Fannie  Agnew.  to  whom  I  am  greatly 
indebted. 

TO  TEACHERS  OF  DENTAL  RADIOGRAPHY 

For  years  I  lectured  to  dental  students  in  an  effort  to  teach  Radiography.  I 
failed  to  get  the  results  I  knezv  I  should  get. 

I  then  wrote  my  book  on  the  subject,  assigned  lessons  in  it  and  quizzed  over 
the  assignments.    And,  again,  I  failed  to  teach  the  subject  as  it  should  be  taught. 


Students  simply  floundered  about  in  the  assignments  and  were  not  able  to  answer 
questions. 

J  wrote  a  compend  on  the  subject,  and  discarded  it,  because,  like  all  compends, 
it  failed  to  cover  the  subject  as  well  as  it  should  be  covered. 

I  theft  read  my  book  {it  is  proof  conclusive  that  a  writer  is  desperate  when 
he  reads  his  own  hook)  and,  as  I  read,  prepared  a  list  of  questions  covering  the 
most  important  points  in  the  text,  and  had  this  list  of  questions  published  in  the 
form  of  a  small  "Assignment  Booklet."  With  this  booklet  and  the  text  book  in  the 
hands  of  the  student  I  can  now  assign  lessons  by  giving  a  certain  number  of  ques- 
tions. After  each  question  in  the  booklet  is  the  number  of  the  page  on  which  the 
answer  may  be  found.  The  questions  are  such  as  to  cause  the  student  to  read  all  of 
the  text  included  in  the  assignment.  Much  longer  assignments  can  be  made  in  this 
way.  The  student  has  something  to  "  hold  to  "  as  he  tackles  his  assignment.  He 
reads  the  text  with  a  feeling  of  security  as  to  what  is  most  important  and  to  be  re- 
membered, instead  of  trying  to  remember  everything  in,  say,  a  thirty-page  assignment 
and  failing  to  remember  anything,  or  becoming  discouraged  and  "  chucking  the 
whole  assignment." 

The  results  of  this  manner  of  teaching  the  subject  have  been  gratifying  beyond 
my  rather  enthusiastic  hopes  for  it.  It  does  not  prepare  students  to  go  forth  and 
straightway  operate  any  X-ray  machine  with  immediate  and  full  success  any  more 
than  a  course  of  study  of  motors  zvould  enable  a  man  to  jump  into  an  automobile 
and  drive  it.  But  it  gives  students  such,  a  fundamental  knowledge  of  the  subject 
that  they  may  take  up  the  work  with  a  feeling  of  confidence  in  themselves. 

This  little  Assignment  Booklet  will  be  found  of  value  also  to  the  man  who  is 
educating  himself. 

H.  R.  R. 

December,  1917. 


■■# 


CONTENTS 


CHAPTER  PAGE 

elementary  Kadiograpby 

L     Electricity          i 

II.     X-Ray  Machines .14 

III.  X-Ray  Tubes  and  the   X-Rays 41 

IV.  Making  Radiographs 65 

Dental  Radiograpby 

V.     Making  Dental  Radiographs 85 

VI.     Reading   Radiographs 136 

VII.     The  Uses  of  the  Radiograph  in  Dentistry 146 

VIII.     The  Dangers  of  the  X-Rays .       .  273 

IX.     Purchasing  a  Radiographic  Outfit 292 

X.     Stereoscopic  Radiography 297 

JHppenaix 

Electricity .       .       .  319 

X-Ray  Machines 320 

X-Ray  Tubes  and  the  X-Rays .  331 

Making  Dental  Radiographs     .       .       .       .       .       .       .       .  341 

Reading  Radiographs 357 

Uses  of   Radiographs  in  Dentistry 416 

The  Danger  of  the  X-Rays 423 

Stereoscopic  Radiography 431 

The  Problem  of  Pulp  Canal  Surgery  and  Oral  Infection       .  437 


Elementary  and  Dental  Raaiograpby. 

CHAPTER  I. 

electricity. 

Dental  radiography  is  the  science  and  art  of  making  pictures  of  the 
teeth  and  contiguous  parts  with  the  X-rays.  Its  place  and  value  in  the 
practice  of  modern  dentistry  will  be  dealt  with  later. 

Before  we  can  produce  X-rays  we  must  have  at  our  disposal  that 
something  called  electricity. 

Electricity  is  a  form  of  energy  closely  related 
Electricity.  to  motion,  light  and  heat.     We  know  it  is  closely 

related  to  motion,  light  and  heat  because  these  forms 
of  energy  can  be  made  to  produce  electricity,  and  electricity  conversely 
can  be  made  to  produce  them.  Electricity  is  discernible  to  but  one  of  the 
special  senses,  namely,  feeling.  It  cannot  be  seen,  heard,  smelled  or 
tasted.  Victims  of  severe  shocks  have  noted  a  peculiar  taste,  which  they 
call  the  taste  of  the  electricity,  but  it  is  my  opinion,  neither  proved  nor 
disproved  as  yet,  that  this  taste  is  due  to  the  presence  of  new  chemical 
bodies  formed  in  the  saliva  by  electrolysis.  In  other  words,  the  passage 
of  the  current  of  electricity  through  the  saliva  causes  chemical  changes 
to  occur,  resulting  in  the  formation  of  new  chemical  bodies,  and  it  is 
these  new  bodies,  not  the  electricity,  that  produce  a  taste. 

When  electricity  passes  from  one  place  to  an- 

€ondUCtor$.  other    the    substance    through    which    it    passes    is 

said  to  be  a  conductor.  A  substance  throueh  which 
electricity  passes  with  great  difficulty,  when  at  all.  is  said  to  be  a  non- 
conductor. Metals  are  the  best  conductors  of  electricity.  Silver  is  the 
best,  then  copper.  Copper  wire  is  the  most  used  of  any  conductor  of 
electricity.  German  silver  carries  electricity  very  reluctantly,  and  bis- 
muth is  the  poorest  conductor  of  the  metals.  It  was  formerly  thought 
that  electricity  traveled  on  the  surface  of  a  conductor,  but  if  this  were 
true  a  round  wire  could  be  made  to  carry  more  current  by  simplv  flat- 
tening it  and  so  making  the  surface  greater;  while,  as  a  matter  of  fact, 


2  ELEMENTARY  RADIOGRAPHY 

the  flattened  wire  would  carry  less,  because  of  the  condensation  of  the 
metal  incident  to  flattening.  The  human  body  is  a  conductor.  Wood, 
glass  and  vulcanite  are  examples  of  non-conductors. 

When  electricity  passes  from  one  place  to  another  through  a  con- 
ductor, what  is  known  as  the  electric  current  is  established. 

There  are  four  kinds  of  electric  currents:    (i) 
0urr<nt$.  The  continuous,  constant,  or  direct  current,  commonly 

designated  D.C. ;  (2)  the  pulsating;  (3)  the  inter- 
rupted; (4)  the  alternating  or  oscillating,  designated  A.C. 

The  direct  current  is  one  in  which  the  electricity  is  presumed  to  flow 
through  the  conductor  in  one  direction  at  a  uniform  rate  of  pressure. 

The  pulsating  current  is  one  in  which  the  electricty  flows  through 
the  conductor  in  one  direction,  but  at  variable  pressure. 

The  interrupted  current  is  one  in  which  the  electricity  flows  through 
the  conductor  in  one  direction  while  in  motion,  but  which  is  completely 
arrested  in  its  flow  at  frequently  recurrent  intervals. 

The  alternating  current  is  one  in  which  the  electricity  flows  through 
the  conductor  first  in  one  direction,  then  in  the  other.  When  the  current, 
flowing  in  a  given  direction,  reverses,  flows  in  the  opposite  direction,  and 
then  resumes  its  original  direction  of  flow,  it  is  said  to  have  completed  a 
cycle.  The  number  of  cycles  occurring  in  a  second  determines  the  fre- 
quency of  the  current.  We  thus  have,  for  example,  a  60-cycle  frequency 
current,  making  sixty  complete  alternations  per  second. 

Electricity  travels  from  one  place  to  another  be- 
PotcntlxK  cause  of  a  difference  in  potential.     The  term  poten- 

tial means  latent,  inactive,  or  stored-up  energy. 
Take  lightning  as  an  example  of  traveling  electricity.  Why  does  it  occur  ? 
One  cloud  has  a  potential,  figuratively  speaking,  of  say  30,  another  of  20. 
These  clouds  approach  close  enough  to  one  another  so  that  electricity 
can  jump  the  atmospheric  gap  between  them,  which  it  does,  passing  from 
the  one  with  a  potential  of  30  to  the  one  with  a  potential  of  20  and 
equalizing  the  potential  of  each  to  25.  The  light  of' lightning  is  caused 
by  the  resistance  of  the  atmosphere  to  the  passage  of  electricity.  If  such 
a  thing  were  possible  and  an  electric  conductor  stretched  from  the  one 
cloud  to  the  other,  the  potentials  would  be  equalized  as  just  described, 
but  without  the  occurrence  of  the  phenomenon  called  lightning,  because 
the  electricity  would  unostentatiouslv  flow  through  the  conductor  instead 
of  through  the  highly  resistive  atmosphere. 

All  electricity-producing  machines  then,  simply  create  a  compara- 
tively hio-h  potential,  so  that  when  a  path  is  afforded — i.  e.,  when  con- 
ductors are  attached  to  the  machine — the  electricity  leaves,  in  its  effort 
to  equalize  potential. 


ELECTRICITY  3 

Electricity  travels  at  an  inconceivably  rapid  rate 
UelOCity^  of  speed,  instantaneous  results  being  obtained  hun- 

dreds of  miles  distant  on  pressure  of  a  button. 
It  is  stated  that  the  velocity  of  electricity  is  about  the  same  as  light,  which 
latter  travels  about  186,000  miles  per  second.  To  comprehend  this  great 
speed  compare  it  to  the  velocity  of  sound,  which  travels  only  1,090  feet 
per  second. 

In  dentistry  and  medicine  the  terms  used  can  often  be  translated 
literally  into  their  meaning.  For  example,  "odontalgia"  is  a  combination 
of  two  Greek  words  meaning  tooth  and  pain ;  "tonsilectomy"  is  a  com- 
bination of  a  Latin  and  a  Greek  word  meaning  tonsil  and  excision.  Elec- 
trical terms  are,  however,  derived  principally  from  proper  names.  For 
example,  volt,  the  unit  of  measurement  of  electric  pressure,  has  no  literal 
meaning  at  all,  but  is  so  called  in  honor  of  Alexander  Volta,  a  great  elec- 
trician.   And  so  with  the  terms  ohm,  watt  and  ampere. 

When   electricity   leaves   the    electricity-produc- 
Uolt.  irig,  or,  if  you  choose,  potential-creating,  machine,  it 

passes  into  the  conductors  at  a  given  pressure. 
This  pressure  is  measured  in  volts,  just  as  pressure  in  a  water-pipe  is 
measured  in  pounds.  The  volt,  then,  is  the  unit  of  measurement  of 
pressure  of  electricity.  Just  what  is  a  "unit  of  measurement"?  Take, 
for  example,  the  unit  of  linear  measurement;  it  is  called  the  "meter,"  and 
and  is  one-ten-millionth  of  the  distance  from  the  equator  to  one  of  the 
earth's  poles.  The  unit  of  linear  measurement,  then,  the  meter,  is  a  definite 
name  applied  to  a  definite  distance.  So  the  volt  is  a  definite  name  applied 
to  a  definite  degree  of  electric  pressure,  or,  which  means  the  same  as 
electric  pressure,  electromotive  force,  designated  E.M.F.  This  force  is 
sufficient  to  maintain  a  current  of  electricity  of  one  ampere  (the  unit  of 
measurement  of  volume  of  electricity)  through  a  resistance  of  one  ohm 
(the  unit  of  measurement  of  resistance  to  the  flow  of  current  offered  by 
an  electric  conductor).  Let  us  then  fix  this  firmly  in  our  minds.  The 
volt  is  the  unit  of  measurement  of  electromotive  force,  or  pressure. 
Though  it  is  not  commonly  used,  the  writer  much  prefers  the  word 
"pressure"  to  "force,"  believing  it  to  more  clearly  express  the  meaning. 

No  conductor  carries   electricity  without  offer- 
Obm.  ing  a  certain  amount  of  resistance  to  its  flow.     This 

resistance,  which  might  be  compared  to  the  friction 
offered  by  the  sides  of  a  pipe  to  the  flow  of  water,  is  measured  in  ohms 
The  ohm,  then,  is  the  unit  of  measurement  of  resistance  offered  to  the 
flow  of  electricity  by  a  conductor,  and  is  equivalent  of  the  resistance 
afforded  by  a  column  of  mercury  having  a  cross-section  of  one  square 
millimeter  and  a  length  of  106.28  centimeters,  at  a  temperature  of  0°  C. 


4  ELEMENTARY  RADIOGRAPHY 

?t  We   have   considered   pressure   and    resistance. 

Jlmpcrt.  Now  we  come  to  the  energy  itself,  which  may  be 

compared  to  the  water  in  a  water-pipe,  and  is  meas- 
ured in  amperes.  The  ampere  capacity  of  an  electric  conductor  cor- 
responds to  the  cross-section  of  a  water-pipe,  which  latter  is  measured  in 
square  inches.  Thus  the  larger  the  pipe,  which  means,  of  course,  more 
square  inches  in  its  cross-section,  the  more  water  it  will  carry ;  and  so 
the  larger  the  electric  conductor  of  a  given  material  the  greater  its  ampere 
capacity,  and  the  more  electricity  it  will  carry. 


^?^js -m- 


W$  A/  5  1 

FIG.  I 


The  analogy  between  the  water  in  the  water-pipe  and  the  electricity 
in  the  conductor  is  not  perfect,  however.  A  given-sized  pipe  will  carry  a 
column  of  water  of  a  given  cross-section  and  no  more,  because  water  is 
practically  non-compressive.  When  the  flow  of  the  water  is  opposed  to 
gravity,  as  when  drawing  water  from  a  faucet,  this  complete  cross-sec- 
tion must  be  obtained,  too — that  is,  the  pipe  must  be  full — before  any 
pressure  will  establish  a  current  through  the  pipe.  Not  so  with  electricity 
in  a  conductor.  A  wire  which  has  a  normal  capacity  of  say  30  amperes 
will  carry  a  current  of  10,  and  it  can  be  made  to  carry  40  or  50  by  in- 
creasing the  pressure,  because  electricity  is  compressible. 

Amperage,  or  the  volume  of  electricity  carried  in  a  conductor,  de- 
pends on  two  things — the  pressure  of  the  current  and  the  resistance  of 
the  conductor.  Hence  Ohm's  law,  which  is  that  the  volume  of  the  current 
can  be  obtained  by  dividing  the  pressure  by  the  resistance.  In  other 
words,  the  amperage  can  be  obtained  by  dividing  the  volts  by  the  ohms. 

Problem :  An  electromotive  pressure  of  100  volts  is  acting  against 
a  resistance  of  50  ohms.  What  is  the  ampere  strength  of  the  current? 
Solution :    100  volts  divided  by  50  ohms  equals  2  amperes. 

To  give  the  exact  amount  of  electricity  represented  by  the  ampere, 
it  is  that  amount  which,  when  passed  through  a  standard  solution  of  sil- 
ver nitrate  in  distilled  water,  will  cause  a  deposition  of  metallic  silver  at 
the  rate  of  1.118  milligrams  per  second. 


ELECTRICITY 


Electromotive   power    (not   electromotive  pres- 

matt  sure  or  force;  note  the  word  "power"),  or  the  ability 

of  a  current  to  do  work,  depends  on  two  things — 

the  pressure  measured   in  volts  and  the  volume  measured   in   amperes. 

This  is  also  true  in  hydraulics.     The  amount  of  work  a  stream  of  water 

will  do  depends  on  pressure  and  volume.     The  watt  is  the  unit  of  meas- 


Fig.  3. 

Fig.   2.     Arrows  A   represent  the   direction   of  flow  of   electric  current.      Arrows   B    represent   the 

direction    of    flow    of    magnetic    flux    in    the    magnet. 

Fig.    3.     Bar    magnet    with    polarity    indicated. 

urement  of  electromotive  power,  and  the  wattage  of  a  current  is  obtained 
by  multiplying  the  volts  by  the  amperes.  Thus,  if  we  had  a  current  of  one 
ampere  under  a  pressure  of  one  volt,  one  watt  would  be  operative. 

When  I, GOO  watts  are  active  for  an  hour — that  is,  when  a  current 
I, GOO  watts  strong  has  been  in  motion,  the  current  turned  on,  for  one 
hour — the  electrometer  will  register  one  kilowatt-hour.  So  bills  for  elec- 
tricity are  made  out  for  so  many  kilowatt-hours. 

Magnetism    is   a    form   of   kinetic   energy   very 
masnetism.  closely    related    in    its    nature    to    electricity.      Mag- 

netism produces  electricity,  and  vice  versa. 


6  ELEMENTARY  RADIOGRAPHY 

The  substance  in  which  this  energy,  or  property,  magnetism,  resides 
is  called  a  magnet. 

If  a  bar  of  magnetized  steel  be  dropped  into  iron  filings,  and  then 
raised,  the  fillings  will  adhere  to  the  ends  of  the  bar,  but  not  to  the  center. 
(Fig.  I.) 

The  ends  of  the  bar  represent,  respectively,  the  north,  or  positive, 
and  the  south,  or  negative,  poles  of  the  magnet.  If.  now,  this  bar  be 
broken  at  its  exact  center,  instead  of  having  a  half  magnet  all  north 
pole  and  another  half  magnet  all  south  pole,  we  have  two  magnets  with 
two  poles  each.  If  one  of  these  magnets  be  broken  at  its  center  the  same 
thing  occurs,  namely,  two  magnets,  each  one-half  as  large  as  the  first, 


Fig.    4.     When   poles   are   arranged   as   in   A   repulsion    exists   between   the   magnets.      VVhen   poles 

are    arranged    as    in    B    the    magnets    are    Attracted    to    one    another    with    the    magnetic    flux    of 

each   north  pole   flowing   into   the   south   pole    of   the    other   magnet. 


are  made.  This  redivision  can  be  repeated  down  to  the  molecule,  which 
would  have  a  north  and  a  south  pole. 

Magnets  are  of  two  kinds — the  natural  magnet,  or  "loadstone,"  and 
the  artificial  magnet. 

The  earth  may  be  considered  a  large  magnet,  the  poles  of  this  mag- 
net being  near  the  north  and  south  poles  of  the  earth.  The  natural  mag- 
net is  iron  ore,  found  in  nature  with  all  the  properties  of  the  magnet,  and 
representing  a  portion  of  the  great  magnetj  the  earth. 

Artificial  magnets  are  of  three  kinds — the  electro-magnet,  the  perma- 
nent magnet  and  the  induced  magnet. 


ELECTRICITY 


7 


If  a  bar  of  soft  iron  be  wrapped  with  insulated  wire  (wire  covered 
with  a  nonconductor)  and  a  current  of  electricity  be  sent  through  the 
wire,  the  iron  bar  becomes  magnetized  while  the  current  passes  through 
the  conductor,  but  loses  its  magnetism  when  the  current  ceases  to  flow, 
r-uch  a  magnet  is  called  an  electro-magnet.  (Fig.  2.)  If  the  current  be 
sent  through  the  conductor  in  the  opposite  direction  to  that  shown  in  the 
diagram,  polarity  of  the  magnet  will  be  changed:  the  north  pole  will 
become  the  south  pole  and  the  south  pole  the  north  pole. 


Fig.  5. 


Fig.   6. 


If  hard  steel,  instead  of  soft  iron,  be  used  as  the  core  and  wrapped 
with  insulated  wire  and  a  current  of  electricity  be  sent  through  the  wire 
for  a  great  length  of  time,  then  the  current  shut  off  and  the  wire  removed. 
it  will  be  found  that  the  steel  retams  its  magnetism  and  will  continue  to 
retain  it  over  a  number  of  years.  Such  a  magnet  is  called  a  permanent 
magnet  (Figs,  i  and  4.  for  example),  though  it  is  not  actually  permanent 
and  will  lose  its  magnetism  in  lime.  The  permanent  magnet  in  greatest 
general  use  is  the  "horseshoe"  magnet  (Figs  4  and  5),  which  is  simply 
the  bar  magnet  (Figs,  i  and  3)  bent  into  horseshoe  or  staple  shape. 

Instead  of  using  the  electric  current,  a  permanent  magnet  can  be 
-made  by  rubbing  hard  steel  Avith  another  magnet. 

Fig.  3  shows  a  magnet  holding  three  nails.     As  long  as  the  magnet 


8 


ELEMENTARY  RADIOGRAPHY 


remains  in  contact  with  the  first  nail  it  will  hold  the  second  nail,  and  the 
second  will  hold  the  third.  But  remove  the  magnet  and  no  attraction 
exists  between  the  nails.  While  the  magnet  touches  the  first  nail  each 
nail  is  an  induced  magnet,  with  a  north  and  south  pole,  as  shown  in  the 
figure. 

While  either  the  north  or  south  pole  of  a  magnet  will  attract  a  piece 
of  unmagnetized  iron  or  steel,  only  unlike  poles  of  two  magnets  will  be 
attracted  to  one  another.  Thus,  if  two  north  or  two  south  poles  of  mag- 
nets be  brought  in  close  proximity  repulsion  instead  of  attraction  exists 
between  them.     (Fig.  4.) 


Fig.    7.     Magneto-Dynamo.      A,    the    magnets    or    field.       B,    casting    surrounding    revolving    con- 
ductor or   armature.      C,   appliance   for   outlet   of   electricity   from   armature.      An   alternating   cur- 
rent  is   generated    by    this    machine. 


In  183 1  Faraday  discovered  that  when  an  electric  conductor  is  set 
in  motion  so  as  to  cut  the  lines  of  force  of  the  magnet  at  right  angles,  an 
electric  current  is  induced  in  the  conductor. 

Fig.  5  shows  the  lines  of  force  of  a  horseshoe  magnet  passing  from 
the  north  to  the  south  pole.  Imagine  now  a  spool  wrapped  with  copper 
wire,  not  as  thread  is  wound  around  a  spool,  but  lengthwise  of  the  spool, 
the  wire  passing  over  its  ends.  Place  this  spool  between  the  poles  of  the 
magnet,  revolve  it  on  its  axis,  and  the  copper  wire — that  is,  the  electric 
conductor — is  made  to  cut  the  force  of  the  magnet  at  right  angles  and  an 
alternating  current  of  electricity  will  be  produced  in  the  wire  (Fig.  6), 
the  current  flowing  in  opposite  directions  as  the  different  poles  are  passed. 


ELECTRICITY  g 

Add  to  this  arrangement  a  means  for  carrying  the  current  away  from  the 
apparatus  and  we  have  the  magneto-dynamo,  now  very  extensively  used 
in  automobiles.     (Fig.  7.) 

Dynamos  may  be  divided  into  two  classes :  the 
Dynamos.  magneto-dynamo,    just    described,    and    the    electro- 

dynamo. 


Fig.    8.     A    Direct    Current    Generator    or    Electro-Dynamo. 


All  dynamos  consist  of  three  cardinal  parts,  to  wit :  the  field,  or  mag- 
nets ;  the  armature,  or  revolving  conductor,  and  the  rings,  or  appliance 
for  carrying  ofif  the  electricity.  If  the  current  sent  out  is  direct  instead 
of  alternating,  a  commutator  instead  of  rings  must  be  used.  A  commu- 
tator is  an  appliance  which  changes  the  alternating  current  induced  in 
the  armature  into  a  direct  current  as  it  leaves  the  dynamo. 

The  electro-dynamo,  an  example  of  which  is  shown  in  Fig.  8,  dif- 
fers in  principle  from  the  magneto-dynamo  only  in  the  kind  of  magnets 
used.  Permanent  magnets  are  used  in  the  magneto-dynamo,  whereas 
electro-magnets  are  used  in  the  electro-dynamo. 

Immense  electro-dynamos,  or  generators,  as  they  are  called,  make 


10 


ELEMENTARY  RADIOGRAPHY 


our  commercial  currents,  steam  power  being  used  to  revolve  their  arma- 
tures. By  commercial  current  is  meant  the  electric  current  supplied  to 
us  by  the  electric  light  and  power  companies. 

Let  us  trace  a  current  of  electricity  through  what  is  known  as  the 
electric  circuit.     When  the  armature  is  revolved  the  potential  at  C,  of 


Fig.    9.     Six   Pole   Direct    Current   Generator,   parts    disassembled.      E,    electro-magnets    with   poles 

of   diliferent    denominations    directly    opposite    one    another — the    field.      Large    alternating    current 

generators    have    as    many    as    40    poles    in    the    field    which    revolves,    the    armature    remaining 

stationary.      A,    armature.      C,    commutator. 


Fig.  7,  rises.  The  potential  of  the  positive  wire  attached  to  binding  post 
-[-(which  post  is  connected  to  C)  is  instantly  raised  to  that  of  C,  and 
the  current  ceases  to  flow,  potential  being  equalized  between  the  arma- 
ture and  the  positive  wire.  If  now  the  positive  wire  of  the  high  poten- 
tial be  brought  in  contact  with  the  negative  wire,  which  is  of  low  poten- 
tial, the  current  flows  into  the  latter.  The  negative  wire  is  attached  to 
the  negative  binding  post,  which  is  connected  to  the  magnets  themselves. 
Thus  the  current  passes  through  the  negative  wire  into  the  magnets, 
which  have  a  low  potential.  The  current  will  continue  to  flow,  making 
a  circuit  from  C,  out  through  the  positive  wire,  back  through  the  nega- 
tive wire,  into  the  magnets  until  their  (the  magnets')  potential  is  raised 


ELECTRICITY 


II 


to  that  of  C.  If  an  incandescent  light  bulb  be  connected  to  the  positive 
and  negative  wires  the  current  will  pass  from  the  positive  wire,  through 
the  bulb,  and  into  the  negative  wire.  As  the  electricity  passes  through 
the  bulb  it  heats  the  filament  of  carbon  to  incandescence,  producing  light 
and  some  heat.  Most  of  the  electricity  is  used  up  in  the  production  of 
the  light  and  heat — this  is  true  if  the  circuit  is  what  is  called  "well  bal- 
anced"— ^but  what  is  not,  travels  in  the  negative  wire  toward  the  magnet, 
equalizing  potential  until  it  dissipates  itself  in  the  effort. 


Fig.    10.      Diagram    of    a    step-down    transformer. 


Commercial  circuits  supply  either  a  D.C.  (direct  current)  or  an  A.C. 
(alternating  current).  The  wiring  from  the  D.C.  dynamo  to  the  consumer 
is  an  intricate  problem,  difficult  to  understand.  It  is  enough  for  us  to 
know  that  the  D.C.  is  supplied,  as  a  rule,  only  to  downtown  districts  of 
cities,  by  a  circuit  giving  no  volts  pressure,  or  a  special  three-wire  cir- 
cuit, which  supplies  either  no  or  220  volts,  according  to  the  manner  of 
the  connections  made  to  the  mains.  The  amperage  depends  on  the  size 
of  the  wires ;  the  more  amperage  desired  the  larger  the  wires  connecting 
to  the  mains  must  be. 

The  A.C.  leaves  the  generator  at  a  voltage  of  from  1,000  to  3,000,  and 
flows  in  the  mains  at  this  pressure.  Such  great  pressure  is  both  danger- 
ous and  uselessly  high  for  ordinary  uses,  such  as  lighting,  running  motors, 
operating  X-ray  machines  and  the  like.  So,  by  means  of  a  transformer, 
the  voltage  is  reduced  to  any  desired  strength,  usually  from  100  to  125 
volts.    The  commercial  A.C.  is  either  25,  60  or  133-cycle,  usually  60. 

Since  the  principle  involved  in  the  transformer  is  quite  similar  to 
the  one  met  with  in  X-ray  machines,  a  description  of  it  would  not  be  out 
of  place  in  this  work.  Fig.  10  shows  the  plan  of  construction  of  a 
transformer.  A  represents  an  iron  core,  around  which  is  wrapped  insu- 
lated wire.  This  is  the  primary  winding  through  which  passes  the  pri- 
mary current  at  the  high  voltage  of  from  1,000  to  3,000.  As  always,  the 
amperage  depends  on  the  size  of  the  wire.     B  represents  another  iron 


12 


ELEMENTARY  RADIOGRAPHY 


core,  around  which  is  also  wrapped  insulated  wire.  This  is  the  secondary 
winding,  through  which  the  secondary  current  passes.  C  shows  soft 
iron  connections  between  the  two  cores. 

When  the  electric  current  is  established  in  the  primary  winding  a 
current  is  set  up  or  induced  in  the  secondary  winding.  Bear  in  mind 
there  is  no  electric  connection  between  primary  and  secondary  windings. 


Fig.    11.     A   Transformer. 


The  primary  current  enters,  and  leaves  unaltered  except  for  a  slight  loss 
in  amperage,  but  in  its  passage  it  induces  a  current  in  the  secondary. 

If  the  wire  used  in  the  secondary  winding  be  of  the  same  length  and 
size  as  that  used  in  the  primary  winding,  the  induced  secondary  current 
will  be  of  practically  the  same  voltage  and  amperage  as  the  primary  cur- 
rent. But  if  the  wire  in  the  secondary  be  shorter  and  larger,  the  induced 
current  will  be  lower  in  voltage  and  higher  in  amperage.  Or  if  the 
wire  of  the  secondary  winding  be  longer  and  smaller  than  the  wire  in 
the  primary  winding,  the  induced  secondary  current  will  be  higher  in 
voltage  and  lower  in  amperage  than  the  primary  current.  The  wattages 
of  the  primary  and  secondary  currents  remain  practically  the  same.  For 
example,  suppose  the  voltage  of  the  primary  current  is  1,000,  the  am- 
perage 5,  the  wattage  would  be  5,000.     Suppose  now,  by  means  of  the 


ELECTRICITY  13 

transformer,  the  voltage  is  lowered  to  100;  there  would  be  a  raise  in  am- 
perage to  50.  Notice  the  wattage  remains  the  same,  5,000.  The  figures 
do  not  represent  what  actually  happens,  since  they  do  not  take  into  ac- 
count the  loss  of  current  due  to  the  internal  or  intrinsic  resistance  of  the 
transformer,  but  they  do  represent  roughly  the  general  principle  of  the 
action  of  the  transformer. 

A  transformer  which  lowers  voltage — the  kind  used  on  A.C.  cir- 
cuits between  mains  and  consumer — is  known  as  step-down  transformer; 
one  which  raises  voltage  is  a  step-up  transformer. 

The  transformer  does  not  alter  the  nature  of  the  current.  That  is, 
the  secondary  is  an  alternating  current,  the  same  as  the  primary,  the 
change  being  only  in  voltage  and  amperage.  Transformers  cannot  be 
used  on  a  direct  current. 

The  foregoing  is  calculated  to  give  the  reader  a  speaking  acquaint- 
ance with  electricity,  the  wonderful  force  which  produces  X-rays.  Fur- 
ther treatises  of  the  subject  will  be  made  as  necessity  demands.  It  will 
be  noted  that  but  one  source  of  electricity  has  been  considered,  namely 
dynamo  electricity— that  furnished  by  light  and  power  companies.  Be  it 
known,  however,  that  electricity  can  be  produced  by  means  other  than  the 
dynamo — by  friction  and  chemical  change,  for  examples.  We  have  con- 
sidered only  the  source  of  electricity  which  is  used  to  operate  the  X-ray 
coils. 


CHAPTER  II. 

X-Kay  machines. 

It  was  stated  in  Chapter  I  that  an  electric  current  is  necessary  to  pro- 
duce X-rays,  but  nothing  was  said  concerning  the  strength  of  the  current 
required.  It  takes  a  current  very  high  in  voltage,  varying  from  about  50.- 
000  to  100,000  or  more  volts,  and  low  in  amperage,  the  amperage  being 
measured  in  milliamperes.  Milliamperage  ranges  from  2  or  3  to  over  100. 
For  dental  radiographic  work  the  milliamperage  used  ranges  from  about 
5  to  60. 

The  ordinary  commercial  circuit  for  lighting  purposes  is  almost  in- 
variably either  D.C.,  no  volts,  or  A.C.,  60-cycle,  100  to  125  volts.  The 
amperage  varies  according  to  the  amount  of  electromotive  power  needed, 
ranging  from  4  to  5  to  over  100  amperes.  The  commercial  current,  as 
supplied,  is  therefore  useless.  However,  it  will  operate  a  machine  which 
will  give  the  desired  current. 

X-ray  machines  are  of  two  classes  :    Those  that 
X-RiV  generate  their  own  electricity  without  any  external 

m<lCl)lnc$«  electric  supply,  and  those  that  depend  on  a  commer- 

cial current  or  storage  batteries  to  excite  them. 
There  is  but  one  of  the  first  class,  namely,  the  static  machine  (Fig.  12), 
and  of  the  second  class  there  are  three — the  Ruhmkorff  coil  (Fig.  13), 
the  high  frequency  or  Tesla  coil  (Fig.  14),  and  the  "interrupterless"  coil 
(Fig.  15).  All  of  the  latter  class  are  literally  induction  coils,  just  as  the 
transformer,  described  in  Chapter  I,  is  an  induction  coil,  but  when  the 
term  induction  coil  is  used  we  may  assume  that  it  is  the  Ruhmkorff  coil 
that  is  referred  to.  We  shall  follow  the  precedent  and  call  the  Ruhm- 
korff coil  the  induction  coil,  though  it  is  no  more  an  induction  coil  than 
the  high-frequency  or  "interrupterless"  coils. 

The  static  machine  is  so  much  inferior  to  the  induction  coil  for  pic- 
ture work,  and  so  large  and  difficult  to  operate,  compared  with  any  coil, 
that  the  only  reason  for  using  it  would  be  the-  lack  of  a  commercial  cur- 
rent with  which  to  operate  a  coil.  Even  in  such  an  event — the  lack  of  a 
commercial  current — I  would  advise  the  use  of  an  induction  coil  operated 
by  storage  batteries  (Fig.  16)  in  preference  to  the  static  machine. 

14 


X-RAY  MACHINES 


15 


The  induction  coil  is  a  popular  apparatus   for 
Induction  giving  the  electric  current  necessary  for  X-ray  pic- 

Coll.  ture  work.     It  is  a  step-up  transformer  to  this  ex- 

tent, namely,  its  primary  current  is  of  comparatively 
low  voltage  and  high  amperage,  while  the  secondary  is  very  high 
in  voltage  and  low  in  amperage.  It  differs  from  the  transformer 
in  mechanical  construction,  and  also  in  that  the  primary  current 
must  be  an  interrupted  current,  and   the  secondary,  induced  current  is 


Fig.    ^2.     A    static    machine. 


practically  a  uni-directional  one.     It  will  be  recalled  that  the  primary  and 
secondary  currents  of  the  transformer  are  both  alternating. 

Let  us  trace  a  current   of  electricity   from  the 
TnitallatiON.  mains  through  an  induction  coil  and  auxiliary  appli- 

ance leading  to  it.     (Fig.  17.) 
Wiring  from  the  mains  to  the  coil  should  always  be  done  by  a  com- 
petent electrician.     A  wire  of  a  given  size  will  carry  only  a  certain  am- 
perage without  heating.     If  this  amperage  be  exceeded  greatly  the  wire 


i6  ELEMENTARY  RADIOGRAPHY 

may  become  hot  enough  to  set  fire  to  surrounding  building  material  of  a 
combustible  nature.  There  are,  therefore,  laws  governing  the  size  of 
wires  to  be  used  to  carry  different  amperages.  Coils  are  rated  by  their 
manufacturers   to    consume   a   certain   number   of   amperes,    and    wiring 


Fig.  13.     Induction  or  Ruhmkorff  coil. 


should  be  done  according  to  this  rating.  The  amount  of  amperage  neces- 
sary to  operate  a  coil  varies  directly  according  to  the  size  of  the  coil — 
the  larger  the  coil  the  more  amperes  it  takes.  Assuming  the  coil  to  be 
of  a  medium  large  size,  the  lead  wires  used  to  connect  it  to  the  mains 
should  be  capable  of  carrying  at  least  30  amperes  without  heating.  By 
"lead  wires"  I  mean  the  wires  leading  to  the  machine — not  lead  (the 
metal)  wires.    The  wires  are  copper. 


X-RAY  MACHINES  17 

Somewhere    near    where    the    wires    enter    the 
fusts.  building,  and  also  at  the  coil  itself,  will  be   found 

fuses.  (Fig.  18.)  A  fuse  is  a  wire,  an  alloy  of 
lead,  of  a  given  size,  and  fusing  point,  capable  of  carrying  only  a  limited 
amperage  without  melting.  Thus,  if  more  than  30  amperes  be  sent 
through  a  30-ampere  fuse,  the  wire  is  heated  to  its  fusing  point,  it  melts, 
the  circuit  is  broken,  and  the  flow  of  electricity  is  stopped.     A  fuse  is  a 


sort  of  safety  valve.  About  30  ampere  fuses  should  be  used  for  a  medium 
large  induction  coil.  This  information,  however,  will  always  be  given 
by  the  manufacturers  of  the  coil. 

Somewhere  near  where  the  wires  enter  the  build- 
$WitCl)CS.  ing,   and  also  at  the  coil,  are  placed  switches.     An 

electric  switch  (Fig.  19)  is  an  appliance  for  throw- 
ing the  electric  current  into,  and  out,  of  an  extended  or  auxiliary  circuit. 

Assuming  that  the  current  at  our  disposal  is  D.C.,  it  must  first  be 
passed  through  an  interrupter. 

An  interrupter  is  an  electric  apparatus  by  means 
Tnttrruptcrs.  of  which  a  constant  current  is  converted  intO'  an  in- 

terrupted one.  Interrupters  are  of  three  kinds:  (i) 
The  electrolytic,  Fig.  20;  (2)  the  mercury  turbine.  Fig.  21,  and  (3)  the 
mechanical  or  vibrator.  Fig.  22. 

For  picture  work,  in  connection  with  the  induction  coil,  the  elec- 
trolytic, or,  as  it  is  sometimes  called  in  honor  of  the  inventor,  the  Weh- 
nelt  interrupter,  is  quite  the  best.     With  it  the  constant  current  may  be 


i8 


ELEMENTARY  RADIOGRAPHY 


interrupted  at  the  rate  of  from  60  to  30,000  interruptions  per  minute. 
The  mercury  turbine  gives  from  200  to  3,600  interruptions  per  minute, 
and  the  vibrator  from  250  to  1,000  interruptions  a  minute. 


Fig.    15.     Interrupterless    coil. 


The  electrolytic  interrupter  consists  of  a  glass  jar  containing  a  solu- 
tion of  sulphuric  acid  in  water,  the  electrolyte,  in  which  is  immersed  a 
platinum  point  electrode,  A  (Fig.  20),  and  a  lead  electrode,  B.  The 
platinum  is  covered  with  a  porcelain  sheath,  Q  except  for  its  point,  which 
projects  into  the  electrolyte.  Little  or  much  of  the  point  may  be  exposed 
in  the  acid  by  the  regulating  arm,  D. 

We  have  two  wires  now  leading  from  the  mains  to  our  apparatus 


X-RAY  MACHINES 


19 


Of  these  one  is  the  positive  wire  which  brings  the  electric  current,  and 
the  other  is  the  negative  or  return  wire.  The  positive  wire  must  be  at- 
tached to  the  binding  post  of  the  platinum  electrode,  marked  -j-.     (Fig. 


Fig.    16.     Induction    coil    for    use    with    storage    cells. 


20.)  But  how  can  we  tell  which  is  the  positive  wire?  Cut  some  of  the 
insulation  oE  the  ends  of  the  wires,  immerse  them  in  a  glass  of  water, 
and  bubbles  will  be  given  off  from  the  negative  wire.  When  making 
this  test,  care  should  be  taken  not  to  touch  one  wire  to  the  other,  so 
making  a  short  circuit.  The  term  (short  circuit)  almost  explains  its'elf. 
The  desired  circuit  in  this  instance  is  from  the  positive  wire,  through  the 
water,  which  is  highly  resistive  to  the  flow  of  electricity,  into  the  negative 
wire  and  back  to  the  mains.     Suppose  that  the  wires  come  in  contact 


20 


ELEMENTARY  RADIOGRAPHY 


(that  portion  of  the  wires  from  which  the  insulation  has  been  removed), 
the  current  no  longer  passes  through  the  water,  but  takes  the  shorter 
path  of  less  resistance,  passing  directly  from  positive  to  negative  wire. 
All  the  amperage  formerly  used  and  choked  back  by  the  resistive  water 
flows  through  the  wires,  heating  them  rapidly. 


regulate  L&nSth,  0/ 
dparH  gap 


/Secondciry^ 


Interrupler 

Fig.   17.     The  spark  gap  between  the   secondary  terminals   is  the   "  parallel  spark  gap." 


The  course  of  the  electric  current,  through  the  electrolytic  inter- 
rupter, is  from  platinum  through  the  acid  electrolyte,  and  on  through 
the  lead  electrode.  As  the  current  flows  through  the  acid  solution,  a 
chemical  change  occurs  and  a  gas  is  formed.  This  gas  accumulates  in 
the  form  of  a  bubble  around  the  exposed  platinum  point,  and  momentarily 
stops  the  flow  of  the  current.  Then  the  bubble  bursts  and  the-  current  is 
re-established  only  to  be  stopped  again  in  the  manner  just  described,  and 
so  on.  The  more  platinum  exposed  in  the  solution  the  slower  the  inter- 
ruptions and  the  more  amperage  will  pass  through  the  interrupter.  In 
order  that  the  amperage  may  be  increased  without  producing  a  corre- 
sponding decrease  in  the  number  of  interruptions  per  minute,  interrupters 
are  made  with  several  platinum  points.  (Fig.  23.)  Thus  with  a  multi- 
point interrupter,  when  more  amperage  is  desired,  more  points  are  thrown 
into  the  circuit  by  means  of  small  switches  for  the  purpose.    A  i  or  2-point 


X-RAY  MACHINES 


21 


interrupter  will  draw  enough  amperage,  and  give  sufficiently  rapid  in- 
terruptions, for  dental  radiographic  work. 

The  current  is  sometimes  stopped  altogether  by  the  interrupter.  This 
may  be  due  to  the  accumulation  of  a  large  bubble  of  gas,  on  the  platinum 
point,  which  will  not  burst.     By  moving  the  point — or  points  if  the  inter- 


Fig.    18.     Patent   fuses    or   cutouts. 


rupter  is  multipointed — up  and  down  several  times  by  means  of  lever  D, 
Fig.  20,  the  bubble  will  be  broken  and  the  current  re-established. 

On  a  D.C.,  iio-volt  circuit  the  electrolyte  should  be  15  to  20  per 
cent,  acid ;  on  a  D.C.,  220-volt  circuit,  from  5  to  8  per  cent,  is  strong 
enough.  The  jar  should  be  one-half  or  three-quarters  full.  As  the  solu- 
tion stands,  some  of  the  water  evaporates,  so  raising  the  per  cent,  of  acid 
in  the  electrolyte.  As  this  occurs,  more  water  should  be  added.  The 
strength  of  the  solution  can  be  easily  and  accurately  determined  by  means 
of  a  hydrometer.  (Fig.  24.)  As  the  water  evaporates,  and  the  solution 
gets  stronger,  its  specific  gravity  raises.  The  hydrometer  is  sensitive  to 
this  change  of  specific  gravity. 

As  the  current  passes  through  the  interrupter,  heat  is  produced. 
Hence  the  glass  jar  is  placed  in  a  metal-lined  box,  and  the  box  filled  with 
water.  (Fig.  23.)  Even  with  this  means  for  cooling,  when  used  con- 
tinuously for  fifteen  minutes  or  longer,  the  electrolyte  becomes  so  heated 
that  the  interrupter  no  longer  works  properly.  In  dental  picture  work, 
though,  the  time  of  operation  is  a  matter  of  seconds.  It,  therefore,  will 
be  understood  that  no  trouble  ever  occurs  due  to  heating  of  the  elec- 
trolyte. 


22 


ELEMENTARY  RADIOGRAPHY 


Fig.  19.  Diagrammatic  illustration  showing  the  action  of  an  electric  switch.  The  single 
arrows  mark  the  course  of  what  we  shall  call  (not  knowing  a  better  name)  the  original 
circuit.  The  double  arrows  mark  an  extended  circuit.  The  drawing  shows  the  switch 
— one  of  the  double  knife  variety — closed.  With  the  switch  open  the  current  could 
not  pass  through  the   extended   circuit. 


X-RAY  MACHINES 


23 


When  the  X-rays  are  used  for  their  therapeutic  value,  long  ex- 
posures are  made;  so  long  that  undue  heating  of  the  electrolytic  inter- 
rupter would  be  sure  to  occur.  Hence,  for  this  work  the  mercury  turbine 
interrupter  (Fig.  21)  is  best.  In  principle  the  mercury  turbine  is  a 
mechanical  interrupter,  depending  on  no  chemical  change  for  its  action, 
being  operated  by  means  of  an  electric  motor.     We  shall  not  consider  it 


Fig.  SO.     Non-water  cooled   one-point  electrolytic  interrupter. 


further,  for  it  should  not  be  used  for  picture  work,  except  in  the  absence 
of  an  electrolytic  interrupter. 

The  mechanical  interrupter,  or  vibrator  (Fig.  22),  is  used  only  on 
the  smallest  coils.  The  principle  on  which  it  operates  is  the  one  involved 
in  the  construction  of  electric  bells ;  Fig.  25  illustrates  the  principle.  A  is 
a  movable  arm  with  fulcrum  at  B.  When  the  current  travels,  the  path 
marked  with  arrows,  the  electro-magnet,  C,  draws  the  movable  arm,  A, 
over  to  it,  breaking  the  circuit  at  D.  When  the  circuit  is  broken  the 
electro-magnet  loses  its  magnetism  and  the  spring,  E,  draws  the  movable 
arm  back,  re-establishing  the  circuit.  The  rapidity  of  interruptions  may 
be  regulated  by  altering  the  strength  of  the  spring.  A  popular  form  of 
vibrator  is  the  ribbon  vibrator  illustrated  in  Fig.  26. 


24 


ELEMENTARY  RADIOGRAPHY 


In  tracing  the  current  directly  from  the  supply 
Kectifisr.  wire  into  the  interrupter,  we  have  assumed,  as  stated, 

that  we  are  receiving  our  supply  from  a  D.C.  circuit 
Suppose,  however,  that  the  only  current  at  our  disposal  is  A.C.,  as  is 
often  the  case.  Most  manufacturers  consider  it  necessary  to  pass  the  al- 
ternating current  through  a  rectifier  (Fig.  27)  before  sending  it  into  the 
interrupter. 

A  rectifier  is  an  electrical  apparatus  by  means  of   which  an  alter- 
nating current  is  converted  into  a  uni-directional,  pulsating  current,  and 


Fig.    21.      Mercury    turbine    interrupter. 


consists  of  a  glass  jar  containing  an  electrolyte,  a  solution  of  ammonium 
phosphate  usually,  in  which  is  immersed  a  steel  electrode  and  an  alumi- 
num electrode.  The  jar,  the  electrolyte,  and  the  two  electrodes  consti- 
tute one  cell.     Fig.  27  shows  a  one-cell  rectifier.. 

With  the  direct  current,  we  are  able  to  test  and  determine  which 
of  the  two  lead  wires  is  positive.  This  is  impossible  with  the  alternating 
current,  because  polarity  changes  at  each  alternation.  Either  of  the  lead 
wires  may  therefore  be  attached  to  the  steel  electrode,  and  a  wire  con- 
nected from  the  aluminum  electrode  to  the  platinum  of  the  interrupter. 
As  long  as  the  aluminum  remains  the  negative  electrode  of  the  rectifier, 
the  current  flows  from  steel  to  aluminum  and  on,  but  when  the  current 
reverses  and  starts  to  flow  from  aluminum  to  steel,  a  chemical  change 
occurs  in  the  aluminum,  making  it  a  non-conductor  and  choking  off  the 
flow.  Thus  a  current  of  60-cycle  frequency,  after  passing  through  a  one- 
cell  rectifier,  becomes  practically   (there  is  a  slight  inverse  current)    a 


X-RAY  MACHINES  25 

uni-directional  current  with  30  interruptions  per  second.  If,  after  passing 
through  the  rectifier,  as  just  described,  the  current  is  an  interrupted  one, 
the  questions  arise:  Why  send  it  through  an  interrupter?  Why  not 
directly  on  to  the  coil?  Because  the  interruptions  are  not  sharp  and 
complete  enough.     The  current  is  pulsating  rather  than  interrupted. 

By  connecting  three  or  four  rectifier  cells  in  a  certain  way  (Fig.  28), 
we  are  able  to  obtain  practically  a  uni-directional,  constant  current. 

If  the  supply  current  is  60-cycle,  as  is  usually  the  case,  the  electrolyte 
in  the  interrupter  remains  the  same  as  for  a  D.C.,  i  lo-volt  circuit,  namely, 


•'■■«\ 


Fig.     23.     Vibrator     or    mechanical    interrupter. 

about  20  per  cent.,  but  if  the  A.C.  supply  is  133-cycle,  the  solution  should 
be  stronger — about  30  per  cent. 

From  the  interrupter  the  current  passes  into  the  rheostat,  as  per 
Fig.  17. 

A  rheostat  (Fig.  29)  is  an  apparatus  by  the  use 
Rheostat.  of  which  we  are  enabled  to  regulate  the  quantity  of 

electricity  entering  an  electric  machine.    The  rheostat 
does  not  have  much  effect  on  voltage. 

Fig.  30  illustrates  the  rheostat.  A  represents  coils  of  wire,  often 
German  silver,  offering  great  resistance  to  the  flow  of  electricity.  When 
the  arm,  B,  is  on  button  i,  the  current  must  pass  through  all  the  re- 
sistive wire  on  its  way  to  the  electric  machine,  induction  coil,  motor,  or 
what  not.  This  resistive  wire  chokes  back  amperage.  On  button,  2, 
there  is  less  resistance ;  on  button.  3  still  less,  until  on  the  last  button  the 
current  passes  directly  into  the  machine.     The  rheostat  illustrated  acts 


26 


ELEMENTARY  RADIOGRAPHY 


also  as  a  switch,  completely  breaking  the  current  when  the  arm,  B,  is  on 
button,  o. 

From  the  rheostat  the  current  passes  into  the  coil  proper,  follows 
the  wire  of  the  primary  winding,  and  passes  back  through  the  negative 
lead  wire  to  the  mains. 


Fig.    33.     Seven-point    electrolytic    interrupter,    water-cooled. 


A  different  method  of  wiring  to  that  shown  in  Fig.  17  is  illustrated 
in  Fig.  31.  At  first  glance  it  seems  that  the  primary  current  is  not  inter- 
rupted, the  interrupter  being  on  the  negative  wire  with  the  current  pass- 
ing through  it  after  passing  through  the  coil.  But  since  the  current  can- 
not enter  the  coil  any  faster  than  it  leaves,  the  manner  of  its  exit  will 
govern  its  entrance,  and  hence  the  current  of  the  primary  is  interrupted 
just  the  same,  whether  the  interrupter  be  placed  on  the  positive  or  nega- 
tive lead  Avire. 


X-RAY  MACHINES 


27 


The  coil  consists  of  a  soft  iron,  cylindrical  core, 

goll,  around  which  is  wrapped  insulated  copper  wire,  the 

primary   winding.      (Fig.  32.)       (The    necessity    for 

good  insulation  will  be  appreciated  if  we  stop  to  consider  what  would 


Fig.  24. 


A  Baume  hydrometer.      For  110  voltb   tliu  electrolyte  in  the  interrupter  should  give 
a  reading  between  20  and  25;  for  220  volts,  between  10  and  15. 


happen  if  the  core  were  wound  with  uninsulated  wire.  If  this  were  done 
the  current  would  not  follow  the  windings  of  the  wire  at  all,  but  would 
choose  the  shorter  path  of  less  resistance,  passing  along  the  iron  core, 
making  a  short  circuit.)  Over  the  primary  winding  is  placed  a  heavy 
insulation  of  mica  or  vulcanite,  and  around  this  is  wound  more  insulated 
wire,  the  secondary  winding.      (Figs.  32  and  33.) 

There  is  positively  no  electric  connection  between  the  primary  and 
secondary  windings.     The  primary  current  passes  through  the  primary 


28 


ELEMENTARY  RADIOGRAPHY 


winding  and  into  the  negative  lead  wire.     But  in  its  passage  it  has  in- 
duced or  created  a  secondary  current  in  the  secondary  winding. 

Coils  are  rated  and  designated  according  to  the  maximum  num- 
ber of  inches  of  atmosphere  the  secondary  current  can  be  made  to  jump. 
As  the  current  jumps  from  one  terminal  to  the  other  of  the  secondary 
winding,  a  spark  occurs,  due  to  the  resistance  of  the  atmosphere  to  the 


/> 


r 


,4 A 


7m 


C        P 


Fig.  25. 


Fig.   26. 


Fig.   25.     A,   movable   arm   with   fulcrum    at   B.      C,    electro-magnet.      D,    break.      E,   spring. 
Fig.    26.     A,    piece    of    ribbon    steel.      B,    point    where    circuit    is    broken.      C,    electro-magnet. 


flow  of  the  current.  When  we  speak  of  a  coil  as,  say  a  i2-inch  coil,  we 
mean  that  the  spark  gap  of  that  coil  is  twelve  inches  long;  that  its  sec- 
ondary current  can  be  made  to  jump  twelve  inches  of  atmosphere.  Coils 
with  parallel  spark  gaps  from  as  narrow  as  about  6  inches  to  as  long  as 
about  40  inches  have  been  manufactured. 

The  induction  coils  manufactured  today  usually  have  a  spark  gap 
of  from  8  to  12  inches.     (See  pages  43  and  44.) 

The  wire  of  the  primary  winding  is  from  about  16-  to  4-gauge ;  of 
the  secondary  from  about  34-  to  29-gauge.  The  length  of  the  wire  in  the 
secondary  is  immensely  greater  than  the  length  of  the  wire  in  the  primary. 


X-RAY  MACHINES 


29 


Fig.    27.     One-cell    rectifier. 


Fig.  28.     Three-cell  rectifier. 


30 


ELEMENTARY  RADIOGRAPHY 


At  each  "make"  and  "break"  of  the  circuit  of  the  primary  current, 
a  current  is  induced  in  the  secondary.  The  secondary  current  induced 
at  the  break  of  the  primary  flows  in  the  same  direction  as  the  current  in 
the  primary,  while  the  current  induced  at  the  make  flows  in  the  opposite 
direction.  Thus  the  secondary  is  an  alternating  current;  but  the  current 
of  the  make  is  so  much  weaker  than  the  current  of  the  break  that,  for, 
practical  purpose,  the  secondary  may  be  considered  a  uni-directional,  pul- 


Fig.  39.     Twenty-nine  button  rheostat. 


sating  current.  The  current  of  the  make  is  what  is  known  as  the  inverse 
current,  and  it  is  the  effort  of  all  coil  manufacturers  to  make  a  coil  giving 
as  little  inverse  current  as  possible. 

The  voltage  of  the  secondary  current  cannot  be  determined  ac- 
curately. Authorities  differ  very  greatly  in  their  estimate  of  the  number 
of  volts  required  to  jump  one  inch  of  atmosphere,  giving  the  figure  as 
low  as  10,000,  and  as  high  as  60,000.  What  voltage  is  required  to  jump 
each  succeeding  inch  after  the  first,  is  also  a  question  shrouded  in  very 
great  uncertainty. 

Estimating  each  inch  of  atmosphere  at  10,000  volts,  which  perhaps 
is  getting  as  near  the  truth  as  possible  at  the  present  time,  the  voltage 


X-RAY  MACHINES 


31 


furnished  by  any  size  coil  can  easily  be  determined.  Figuring  on  this 
basis,  an  8-inch  coil  in  full  operation  supplies  a  current  with  a  potential 
of  80,000  volts;  a  20-inch  coil,  200,000  volts. 

The  amperage,  or,  to  be  more  exact,  the  milliamperage  of  the  sec- 
ondary current  of  an  induction  coil  varies  according  to  the  resistance 


Fig.    30.     Diagram    of   rheostat. 


through  which  the  current  is  forced.  Thus,  allowing  the  rheostat  to  re- 
main on  the  same  button,  the  milliamperage  is  increased  or  decreased 
accordingly  as  the  spark  gap  (Fig.  17)  is  shortened  or  lengthened.  With 
the  spark  gap  at  its  maximum  length,  the  milliamperage  is  least.  As  the 
sliding  rods  are  pushed  closer  to  one  another,  so  lessening  the  length  of 
the  spark  gap,  milliamperage  increases.  Different  coils  are  capable  of 
forcing  different  milliamperages  through  their  maximum  length  of  spark 
gap.     Thus  one  lo-inch  coil  may  be  able  to  force  twenty  milliamperes 


3^ 


ELEMENTARY  RADIOGRAPHY 


through  ten  inches  of  atmosphere,  while  another  could  send  only  two 
milliamperes  through  such  a  resistance.  All  coils  give  a  high  milliam- 
perage  on  a  short  spark  gap,  the  amount  running  into  hundreds  of  mil- 
liamperes. Instead  of  the  sliding  rods,  some  coils  have  an  arrangement, 
as  per  Fig.  34,  fcir  regulating  the  length  of  spark  gap. 

The   milliamperage   strength   can   be   estimated   roughly  by  the   ap- 
pearance of  the  spark.     A  thin,  blue  spark  indicates  low  amperage.     A 


Mains 


Coi/l 


Fig.   31. 


fat,  fuzzy  spark,  the  caterpillar  spark,  indicates  high  milliamperage.  To 
do  rapid  dental  radiographic  work  a  coil  should  give  at  least  six  inches 
of  the  fat,  fuzzy  spark. 

Amperemeters  and  milliamperemeters  are  used  on  the  primary  and 
secondary  currents,  respectively,  to  measure  their  volume.  (Fig.  13.) 
While  these  meters  may  be  considered  luxuries  rather  than  necessities, 
they  are  certainly  very  useful  luxuries. 


X-RAY    TUBES   AND    THE    X-RAYS 


33 


Fig.  32. 

A,  iron  core.     B,  iron  core  with  primary  winding.     C,  iron  core,  primary  winding  and  insulation. 
D,   iron  core,   primary   winding,   insulation   and   secondary   winding. 


Now   let   us   consider   the   high-frequency   coil. 
Ulflb-TrCflWency         (Figs-   14  and  35.)      In  mechanical  construction  the 
€Oil.  high-frequency   coil   may  be   considered   a   kind   of 

double  coil  with  the  secondary  of  the  first  coil  act- 
ing as  the  primary  of  the  second  coil.  The  primary  current  of  the  first 
coil  should  be  A.C. 


34  ELEMENTARY  RADIOGRAPHY 

From  the  supply  wire  the  current  passes  through  the  primary  wind- 
ing of  a  step-up  transformer  (first  coil)  at  the  usual  commercial  lOo  to 
125  volts,  60-cycle.  (Fig.  35.)  An  alternating  current  of  the  same 
frequency  as  the  primary,  but  higher  in  voltage  and  lower  in  amperage 
is  generated  in  the  secondary  of  the  transformer,  and  passes  into  the 
condenser,  which  acts  as  a  reservoir.  As  the  current  leaves  the  condenser 
and  jumps  the  regulating  spark  gap,  it  is  oscillating  at  a  frequency  of 


'A 
B 
C 


Fig.   33 

Cross-section    diagram    of    induction    coil.       A,    iron    core.       B,    primary    winding.       C,    insulation. 

D,    secondary   winding. 


from  10,000  to  more  than  a  million.  It  passes  through  the  primary  wind- 
ing of  the  Tesla  coil,  inducing  a  secondary  current  of  the  same  high 
frequency.  This  Tesla  coil  is  the  same  as  an  induction  coil  (Figs.  32  and 
33),  except  that  some  inert  substance,  instead  of  soft  iron,  is  used  for 
the  core. 

The  secondary  current  of  the  second  coil  is  the  one  supplied  by  the 
machine,  the  one  to  be  used  to  generate  X-rays.  Like  the  current  of  the 
Ruhmkorff,  or  induction  coil,  this  current  is  high  in  voltage  and  low  in 
amperage.  The  current  of  the  induction  coil  is,  however,  practically  a 
uni-directional  one,  while  the  current  supplied  by  the  high-frequency  coil 
is  alternating  at  the  inconceivably  high  frequency  of  tens  of  thousands 
or  millions.  Hence  the  term  "high  frequency,"  which  is  applied  to  the 
current  and  the  coil  producing  it. 

The  frequency  is  governed  by  the  size  of  the  condenser;  the  smaller 
the  condenser  the  higher  the  frequency.  Thus  most  "high-frequency  and 
X-ray  machines"  are  equipped  with  a  switch,  by  means  of  which  all,  or 


X-RAY  MACHINES 


35 


a  part,  of  the  condenser  may  be  used.  When  using  the  coil  for  X-ray 
work,  this  switch  should  be  turned  to  "low  frequency,"  so  that  all  of  the 
condenser  is  used.  When  using  the  coil  for  "high-frequency"  treatments 
— using  the  current  as  a  therapeutic  agent — the  switch  should  be  on  "high 
frequency,"  so  that  only  a  part  of  the  condenser  is  used. 

By  means  of  the  regulating  spark  gap,  we  can  control  to  an  extent 
the  secondary  current  of  the  second  coil — the  current  supplied  by  the 


Fig.   34. 


machine  for  use.  Widening  the  gap  increases  voltage  at  the  expense  of 
the  amperage ;  narrowing  the  gap  increases  amperage  at  the  expense  of 
the  voltage.  The  wattage  remains  the  same.  For  X-ray  work  the  gap 
should  be  as  short  as  possible,  without  reducing  the  voltage  to  a  point 
where  the  current  will  not  pass  through  the  X-ray  tube. 

High-frequency  or  Tesla  coils  are  often  spoken  of  as  "  suitcase  coils  " 
and  "  portable  coils,"  because  they  are  frequently  built  in  the  shape  of  a 
suitcase  and  are  transportable. 

Some  coils  of  this  type  are  mere  toys,  incapable  of  doing  good  dental 
work,  while  others  compare  favorably,  on  the  A.C.  circuit,  with  small  and 
medium  size  induction  coils.  One  should  be  cautious,  therefore,  when 
purchasing  a  coil  of  this  type. 


36 


ELEMENTARY  RADIOGRAPHY 


As  stated,  the  primary,  or  supply,  current  of  a  coil,  built  on  the  high- 
frequency  plan  illustrated,  should  be  A.C.  When  attaching  the  portable 
coil  (Fig.  14)  on  an  A.C.  circuit,  therefore,  all  that  needs  to  be  done  is 
to  screw  the  attachment  into  a  lamp  socket. 


Terminal  Sparh  Gap 
(Ab?  rejalatinj  Spark  ^ip) 


^nd  Coil  F^ 

Tesla.  Coil     '~^ 


Spark  (s3.p 


+3 


Comien^er 


PJGoil 
or 

Step -Up 
Transformer 


^econda-ry 


Prtma-fy 


Fig.  35. 


Kotary 
Converter. 


When  the  supply  current  is  D.C.,  a  rotary  con- 
verter should  be  used.  A  rotary  converter  (Fig.  36) 
consists  of  an  electric  motor  set  in  motion  by  the 
supply  current,  which  motor  in  turn  revolves  the 
armature  of  an  A.C.  dynamo,  which  generates  the  electricity  that  is  sent 
into  the  coil.  Instead  of  having  the  D.C.  motor  and  the  A.C.  generator 
as  separate  machines  connected  by  a  common  shaft,  so  that  movement  of 
the  armature  of  one  machine  revolves  the  armature  of  the  other,  the 
rotary  converter  can  be  made  so  as  to  be  enclosed  in  one  casing.  (Fig.  15.) 
Tracing  the  current,  as  per  Fig.  37,  coming  through  the  fuse  and 
switch,  the  current  pagses  through  the  positive  wire  to  the  starting  box 


X-RAY  MACHINES 


37 


or  rheostat.  It  leaves  the  starting  box  through  two  wires,  passing 
through  one  to  the  field  of  the  motor  marked  S.F.,  through  the  other  to 
the  armature  of  the  motor,  marked  ARM,  and  out  of  the  motor  through 
the  negative  lead  wire.  A  new  circuit  is  formed  from  the  generator  side 
of  the  converter  marked  A.C.,  passing  through  the  coil. 

It  may  be  well  to  state  just  here  that  an  electric  motor  is,  in  con- 
struction, practically  the  same  as  a  dynamo  or  generator.     In  fact,  taking 


Fig.    36.     Rotary    converter,    or   motor-dynamo. 


a  given  machine,  it  may  be  used  as  either  a  dynamo  or  a  motor.  If  its 
armature  is  revolved  by  some  power,  it  will  generate  electricity,  and  it 
is  then  a  dynamo ;  if  a  current  of  electricity  is  sent  into  its  field  and 
armature,  the  armature  revolves ;  and  it  is  then  an  electric  motor.  Motors 
are  made  to  be  operated  by  both  D.C.  and  A.C.  circuits ;  that  is,  we  have 
D.C.  motors  which  can  be  run  only  by  a  direct  current,  and  A.C.  motors 
which  can  be  excited  only  by  an  alternating  current. 

Instead  of  a  rotary  converter,  some  machines  are  equipped  with  a 
mechanical  vibrator  (Fig.  22),  which  interrupts  the  current  as  it  enters 
the  coil.  This  is  not  so  efficacious  as  the  converter.  Machines  with  the 
mechanical  interrupter  are  advertised  to  operate  on  either  A.C.  or  D.C. 
circuits. 

The  length  of  the  spark  gaps  of  portable  machines  varies  from  four 
to  ten  inches.  They  are  seldom  able  to  give  a  fat,  fuzzy  spark  longer 
than  half  the  length  of  the  spark  gap.  The  full-length  spark  is  almost 
always  thin  and  blue. 


38 


ELEMENTARY   RADIOGRAPHY 


Tnterruptcrlcss 

€oi1$  or 
transformers. 


The  interrupterless  coil,  or  transformer,  as  it  is 
usually  designated  now,  is  the  newest,  the  easiest  to 
operate  and  the  most  powerful  X-ray  machine  thus 
far  made.  Comparatively  little  space  is  needed  to  ex- 
plain the  principle  of  its  construction,  since  it  will  not  be  necessary  now 
for  me  to  define  and  explain  such  common  electrical  apparatus  as  fuses, 
switches  and  the  like,  as  it  was  in  the  description  of  the  induction  and 
high-frequency  coils. 


Line, 
110  Direct  Current. 


Portable  Coil. 


converter 


Fif 


The  transformer  X-ray  machine  consists  of  a  rotary  converter,  or 
synchronous  motor,  a  step-up  transformer,  and  a  rectifier  switch.  (Fig. 
38.)  The  step-up  transformer  may  be  of  the  closed  magnetic  circuit 
core  type  (Fig.  38B),  or  the  open  core  type  (Fig.  38A).  These  machines 
are  of  two  kinds :  those  built  to  be  operated  on  a  D.C.  circuit,  and  those 
designed  for  the  A.C.  circuit. 

Let  us  consider  the  former  first :  The  converter  is  set  in  motion  by 
the  commercial  direct  current.     It  generates  an  alternating  current  which    ■ 
is  sent  through  the  primary  of  the  transformer.     The  induced  current  in 
the  secondary  is  of  the  proper  voltage  and  amperage  for  X-ray  work, 
but  it  is  alternating.     It  should  be  direct.     It  is  made  so  by  means  of  the   -^ 


X-RAY   MACHINES 


39 


rectifying  switch,  and  is  then  an  ideal  current  for  X-ray  work.  The  rec- 
tifying switch  is  a  revolving  mechanical  device  similar  to  a  commutator 
In  principle. 

Instead  of  a  rotary  converter  the  A.C.  machine  has  an  A.C.  motor, 
on  the  shaft  of  which  is  the  rectifier  switch.    From  the  mains,  four  wires 


ZQ 


T.Q-A-      ,4 


0^  TRKULUtL  1 


fiQ-  56 


Fig.  38.     Didactic  drawing  of  the  transformer  or  interrupterless  X-ray  machine.     "  A  "  the  D.C. 
machine.     "  B  "  the  A.C.  machine.     To  trace  the  current,  follow  the  arrows  by  number. 


lead  to  the  A.C.  machine ;  two  for  the  motor,  two  for  the  transformer. 
First  the  motor  is  set  in  motion.  Then  the  current  may  be  turned  into 
the  primary  of  the  transformer  and  an  alternating  current  is  immediately 
generated  in  the  secondary  winding.  This  secondary,  alternating  current 
is  of  the  proper  voltage  and  amperage  for  X-ray  work,  and  is  made  uni- 


40  ELEMENTARY  RADIOGRAPHY 

directional  by  passing  it  through  the  rectifier  switch.  In  order  for  the 
rectifier  switch  to  change  the  alternating  current  into  a  direct  one  it  must 
revolve  at  a  definite  rate  of  speed,  in  perfect  synchronism,  or  step,  with 
the  rapidity  of  alterations  of  the  alternating  current.  Because  of  this, 
the  motor  is  spoken  of  as  a  synchronous  motor. 

The  first  interrupterless  coils  to  be  made  for  the  alternating  current 
had  an  A.C.  motor  connected  with  an  A.C.  generator.  But  two  main 
wires  lead  to  this  type  of  machine.  The  motor  is  set  in  motion  with  the 
supply  current.  The  shaft  of  the  motor  extends  to  the  generator,  revolv- 
ing its  armature.  The  current  produced  by  the  generator  passes  into 
the  primary  winding  of  the  coil,  and  the  secondary,  induced,  alternating 
current  is  made  direct  by  passing  through  the  rectifier  switch  which  is 
attached  to  the  shaft  of  the  generator  and  therefore  moves  in  synchron- 
ism with  it.  It  was  necessary  to  build  interrupterless  coils  for  the  A.C. 
circuit  in  this  manner  until  motors  were  produced  which  revolve  the  rec- 
tifier switch  in  synchronism  with  the  line  or  supply  current. 

The  greatest  shortcoming  of  the  transformer  type  of  coil  has  been 
the  difficulty  in  making  one  with  sufficiently  high  voltage  to  do  certain 
kinds  of  X-ray  work  as  well  as  the  induction  coil.  This  shortcoming, 
however,  has  been  quite  satisfactorily  overcome. 

The  interrupterless  coils  are  rated  according  to  the  amount  of  "  en- 
ergy "  they  create,  not  according  to  their  spark  gap  length.  The  spark 
gap  is  usually  ten  or  twelve  inches  long.  The  machines  are  rated  to  have 
a  capacity  of  so  many  kilowatts.  Take  a  "  4  kilowatt "  machine,  for  ex- 
ample. Its  primary  current,  we  will  say,  is  100  volts,  40  amperes  (4,000 
watts),  the  secondary  current  something  like  100,000  volts,  40  milli- 
amperes  (4,000  watts). 

This  system  of  rating  is  being  adopted  by  manufacturers  of  induction 
coils  also.     (See  pages  43  and  44.) 


CHAPTER  III. 
X-Kay  tubes  and  the  X-Kay$. 

Thus  far  we  have  considered  only  the  electric  phase  of  the  subject. 
We  shall  now  describe  the  apparatus  through  which  the  electricity  is 
passed,  and  which  generates  the  X-rays,  namely  the  X-ray  tube. 

An  X-ray  tube  is  a  bulbular  glass  tube,  from  which  the  atmosphere 
has  been  exhausted  to  quite  a  high  degree  of  vacuum — about  1/1,000,000 
part  of  an  atmosphere.  It  should  be  remembered  that  there  is  a  some- 
thing which  occupies  all  space,  even  vacuua,  and  that  something  is  known 
as  ether.  There  is,  of  course,  ether  in  the  X-ray  tube.  X-ray  tubes  are 
often  called  Crooke's  tubes,  but  they  resemble  the  tube  made  by  Pro- 
fessor Crooke  only  in  having  a  high  degree  of  vacuum.  In  mechanical 
construction  they  are  quite  different. 

Tubes  may  be  divided,  according  to  the  machines 
Classification  on  which  they  are  used,  into  the  static  machine  tube, 

Of  X-Ray  Cubes.         the  induction  coil  tube,  the  high-frequency  coil  tube 
and  the  transformer  tube. 

Since  we  have  eliminated  the  static  machine  from  consideration  be- 
cause it  is  obsolete  we  will  likewise  eliminate  the  static  machine  X-ray 
tube  and  describe  first  the  induction  coil  tube.  For  a  description  of  the 
Coolidge  tube  see  index. 

In  describing  the  tube  used  with  induction  coils 
TnaUCtion  ^g   of  necessity,  consider  the  fundamentals  of  all  X- 

*  ray  tube  construction  and  X-ray  production. 

Sealed  in  the  X-ray  tube  are  the  anode,  Fig.  39,  A  (also  called  anti- 
cathode  and  target),  and  the  cathode,  B.  The  anode  is  usually  flat, 
placed  at  an  angle  of  45  degrees  to  the  long  axis  of  the  tube,  and  made 
of  some  high-fusing  metal,  such  as  tungsten,  platinum,  iridio-platinum 
or  tantalum.  The  cathode  is  concave,  saucer  shape,  and  usually  made 
of  aluminum. 

Since,  in  connecting  the  tube  to  the  coil,  it  is  necessary  to  attach  the 
connecting  terminal  tape  or  wire  from  the  positive  side  of  the  coil  to  the 
target  end  of  the  tube,  we  must  be  able  to  determine  which  is  the  positive 
terminal  of  the  coil.  This  may  be  done  on  an  induction  coil,  as  follows : 
Cut  out  the  resistance  of  the  rheostat,  adjust  the  sliding  rods  to  about 
one-half  the  distance  of  the  maximum  spark  gap,  and  throw  on  the 
switch.  The  spark  will  jump  the  gap  so  quickly  that  it  is  impossible  to 
learn  by  simple  observation  in  which  direction  it  is  traveling.     By  watch- 

41 


42 


ELEMENTARY  RADIOGRAPHY 


mg  the  large  disc  terminal,  however,  this  can  be  determined.  If  on 
throwing  the  switch  on  and  off  the  spark  is  noticed  to  cling  to  the  edge 
of  the  disc  ahvays,  then  the  current  is  passing  from  the  disc.  If,  how- 
ever, the  spark  occurs  from  the  surface  of  the  disc  just  as  the  current  is 
turned  on  (it  may  then  seek  the  edges),  the  current  is  traveling  from  the 
small  bulb  to  the  disc.     (Fig.  40.) 

With   the  tube  properly  connected  to  the   coil  as  per  Fig.  41,  the 
current  is  shunted   (Fig.  42)   through  the  tube,  instead  of  jumping  the 


+ 


cC 


Fig.   39.     A,   anode.      B,   cathode.      C,  point  at  which  the   atmosphere   was  pumped   from   the   tube. 


spark  gap,  passing   from  anode  to  cathode.     Whether  the  current  will 

choose  the  path   through   the  tube  or  jump  the  spark  gap  depends  on 

which  offers  the  less  resistance.     A  current  of  electricity  always  travels 

the  path  of  least  resistance. 

^,     .^,     .       ^  Tubes  are  designated  according  to  the  degree  of 

Classification  of  .    .  „,  ^        ,        ^u    u-  u       u    a  ^  u 

X-Rav  tubes  their  vacuum.    Thus  we  have  the  high  or  hard  tube, 

Hccordiltfl  to  Degree        in  which  the  vacuum  is  well-nigh  complete  ;  the  me- 

Of  Uacuttm  dium  tube  in  which  the  vacuum  is  less  complete,  and 

the  soft  or  low  tube,  in  which  the  vacuum  is  least  complete.     High  tubes 

offer  the  greatest  resistance  to  the  passage  of  the  electric  current  through 

them,  then  comes  the  medium,  while  the  low  vacuum  tube  offers  the  least 

resistance.   For  dental  picture  work  a  medium  tube  yields  excellent  results. 

The   operator  may  determine  whether  a  tube  is  hard,   medium  or 

soft,  as  follows:    Connect  the  tube  to  the  coil.     (Fig.  41.)     Separate  the 

sliding  rods  to  give  a  spark  gap  of  two  or  three  inches  and  turn  on  the 

current.     Unless  the  tube  is  very  low  indeed,  the  current  will  jump  the 

spark  gap  instead  of  passing  through  the  tube.     Let  us  suppose  the  cur- 


X-RAY  TUBES  AND   THE  X-RAYS 


43 


rent  does  jump  the  spark  gap.  Now  widen  the  gap  a  little;  turn  on  the 
current,  and  it  passes  through  the  tube.  The  tube  will,  therefore,  be 
rated  as  one  of  low  vacuum,  offering  a  resistance  slightly  greater  than 
two  or  three  inches  of  atmosphere.  When  the  current  jumps  the  spark 
gap  instead  of  passing  through  the  tube,  the  tube  is  said  to  have  "backed 
up"  so  many  inches — the  number  of  inches  of  the  gap — of  "parallel 
spark."     Thus  a  low  tube  will  back  up  two  or  three  inches  of  parallel 


A 


«^ 


r 


A 


A 


4- 


A 


i^^ > 

Fig.    40. 


Spark;  a  medium  tube  will  back  up  four  or  five  inches  of  spark;  a  high 
tube  will  back  up  six  or  seven  inches  of  spark,  and  a  very  high  tube  will 
back  up  eight  or  nine  inches  of  spark.  Very  high  tubes  offer  so  much 
resistance  that  only  the  largest  coils  are  able  to  force  sufficient  milliam- 
perage  through  them  to  generate  a  sufficient  number  of  X-rays  for  picture 
work.  A  tube  that  will  back  up  more  than  nine  inches  of  spark  is  too 
high  to  be  useful ;  it  is  impossible  to  force  enough  milliamperage 
through  it.    The  best  back  up  for  dental  work  is  about  5  inches. 

From  the  foregoing  it  will  be  seen  that  any  coil  smaller  than  one 
with  a  7  or  8-inch  spark  gap  could  not  well  excite  a  high  tube,  and  that 
at  least  a  ten-inch  coil  is  necessary  to  light  a  very  high  tube.  It  seems, 
too,  that  any  coil  with  a  spark  gap  wider  than  eight  or  ten  inches  is  need- 
lessly large.  The  coils  with  the  long  spark  gaps  are,  however  seldom 
able  to  throw  a  fat,  fuzzy  spark  farther  than  eight  or  ten  inches.  The 
.throwing  of  a  thin,  blue  spark  a  greater  distance  is  simply  incidental  and 


44 


ELEMENTARY  RADIOGRAPHY 


without  practical  usefulness.  Thus  an  eight  or  ten-inch  coil  may  be  as 
powerful  as  one  with  an  eighteen  or  thirty-inch  spark  gap;  that  is, 
capable  of  forcing  as  high  a  milliamperage  through  a  high  tube.  If, 
however,  a  coil  can  force  any  kind  of  a  spark  at  all  through  from  eighteen 
to  thirty  inches  of  atmosphere,  we  may  be  sure  it  will  send  a  high  milliam- 
perage through  a  good  radiographic  tube,  or,  what  is  the  tube's  equivalent 


Fig.    41.     The    X-ray    tube    connected    with    the    induction    coil. 

in  resistance,  six  or  eight  inches  of  atmosphere.  It  is  so  well  understood 
to-day  that  the  coil  with  the  very  wide  spark  gap  is  not  necessarily  more 
powerful,  that  manufacturers  are  making  practically  all  of  their  coils 
with  from  an  eight  to  a  twelve-inch  spark  gap,  then  rating  them  ac- 
cording to  the  milliamperage  they  can  force  through  this  resistance. 

To  light  a  tube  well  a  coil  should  be  capable  of  giving  a  fat,  fuzzy 
spark,  the  distance  of  the  parallel  spark  which  the  tube  backs  up. 

The  tube  thus  far  described  is  the  simplest  form  of  X-ray  tube,  and 
no  longer  in  general  use.  Next  in  simplicity  is  the  bi-anodal  tube.  (Fig. 
43-) 

When  the  two  anodes  are  connected,  as  in  Fig. 

Bi-anodal  43.  the  positive  terminal  may  be  attached  to  either 

tubes.  anode  or  assistant  anode,  preferably  the  anode.    The 

advantage  of  the  assistant  anode  is  a  matter  on  which 

authorities  have  widely  different  opinions.     One  manufacturer,  a  man 


X-RAY  TUBES  AND  THE  X-RAYS 


45 


who  is  making  one  of  the  very  best  tubes  on  the  market,  tells  me  that  he 
puts  the  assistant  anode  in  his  tubes  because  some  of  his  customers  de- 
mand it,  and  he  is  able  to  do  so  without  impairing  their  efficiency;  that 
his  tubes  would  be  just  as  good  with  but  one  anode.  Remember  the 
vacuum  of  an  X-ray  tube  is  not  perfect ;  there  are  some  gases  in  the  tube. 
The  function  of  the  assistant  anode  is  to  draw  these  gases  back  of  it 
away  from  between  anode  and  cathode.     Thus,  if  the  removable  wire 


m- 


RESISTANCE 


nAAAAAWWA 


m^ 


^ 


THE  SHUNT 

Fig.    42.     The   arrows   show    the    current    flowing   through    the    shunt. 


connecting  the  anode  and  assistant  anode  (Fig.  43)  be  removed  and  the 
tube  hitched  to  the  coil,  the  positive  terminal  being  attached  to  the  anode, 
the  tube  will  work  with  a  slightly  lower  vacuum,  because  the  assistant 
anode  does  not  draw  gases  back  of  it.  Tubes  with  assistant  anodes  are 
supposed  to  be  capable  of  transmitting  a  greater  milliamperage. 

In  the  past  tubes  were  classified  as  tubes  with  a  means  of  regulating 
vacuum' (Fig.  44)  and  tubes  without  a  means  of  regulating  their  vacuum 
(Figs.  39  and  43). 

Tubes  without  regulators  are  no  longer  in  general  use,  because,  with 
use,  they  soon  become  too  hard,  and  must  be  sent  back  to  the  manufac- 
turers to  be  opened  and  repumped.  This  is  expensive  and  annoying.  A 
tube  too  high  for  use  will  sometimes  drop  in  vacuum  and  regain  its 
former  usefulness  if  allowed  to  rest — remain  unused — for  a  month  or  so. 

There  are   different  methods  of   regulating  the 

111(t1)0d$  of  vacuum  of  X-ray  tubes.     The  most  popular  is  the 

Kcgulatins  one  we  shall  now  consider. 

Uacuum.  The  vacuum  is  governed  by  means  of  a  movable 

arm,  which  increases  or  decreases  the  distance  be- 


46 


ELEMENTARY  RADIOGRAPHY 


tvveen  A  and  B,  Fig.  44.  This  distance  we  shall  call  the  tube-regulating 
spark  gap.  The  shorter  the  gap  the  lower  the  vacuum  can  be  made ;  that 
is,  the  shorter  the  gap  the  less  perfect  the  vacuum  can  be  made. 

The  current  enters  the  tube  and,  let  us  imagine,  tries  to  pass  from 
anode  to  cathode.    The  vacuum  in  the  center  of  the  tube  is  more  perfect 


REMOVABLE 
WIRE 


ASSISTANT 
"ANODE 


> 


CATHODE 


ANODE 

Fig.    43.     A    Bi-Anodal    X-ray    tube. 


REGULATING  CHAMBER 


Fig.    44.     X-ray    tube    with    vacuum    regulator. 


than  around  the  walls.  Hence  the  path  of  least  resistance  Is  through  the 
regulating  chamber,  through  the  movable  arm,  through  the  tube-regu- 
lating spark  gap,  into  the  negative  terminal  tape;  unless,  of  course,  the 
tube-regulating  spark  gap  is  very  wide. 


X-RAY  TUBES  AND  THE  X-RAYS 


47 


Fig.    45.      Showing   the    manner    of    connecting   the    third    terminal    on    the    coil    with    the 

regulating  chamber. 

The  regulating  chamber  contains  asbestos  impregnated  with  some 
chemical,  sodium  or  potassium  hydrate,  for  examples.  When  the  current 
passes  through  the  regulating  chamber,  heat  is  created,  which  causes  the 
chemical  to  give  off  gases.  These  gases  lower  the  vacuum  of  the  tube, 
so  that  the  current  may  pass  directly  from  anode  to  cathode.    When  the 


48 


ELEMEN TA R Y  RADIO GRAPHY 


tube  cools  thoroughly — in  the  course  of  fifteen  to  thirty  minutes — these 
gases  are  taken  up  again  by  the  chemicals  in  the  regulating  chamber, 
and  the  vacuum  rises  again.  Thus  the  vacuum  of  the  tube  may  be  too 
high  when  the  tube  is  not  in  use,  but  can  be  lowered  to  the  desired 
degree.      Ordinarily    the    tube-regulating    spark    gap    should    be    three 


CATHODE 
STREAM 


Fig.    46.      Showing   the    direct    X-ray    and    the    cathode    stream. 


to  five  inches.     As  the  tube  gets  old  the  tube-regulating  spark  gap  must 
be  made  shorter  to  obtain  the  same  condition  of  tube. 

When  the  tube  is  properly  hitched  to  the  coil,  and  the  movable  arm 
set  for  a  high  vacuum — to  give  a  regulating  spark  gap  of  about  four 
inches — and  the  current  turned  on,  practically  all  the  current  may  at  first 
pass  through  the  regulating  chamber  and  jump  the  tube-regulating  spark 
gap.  As  explained,  this  lowers  the  vacuum,  and  in  a  few  seconds  the 
current  is  passing  from  anode  to  cathode.  All  of  the  current  may  pass 
directly  through  the  tube  now  for  a  few  seconds,  but  the  passage  of  the 
current  from  anode  to  cathode  raises  the  vacuum  and  presently  some 
current  will  be  seen  to  jump  the  gap  for  a  while.  And  so  on,  just  as  the 
vacuum  raises  a  little,  it  is  immediately  lowered  by  some  of  the  current 
passing  through  the  regulating  chamber. 


X-RAY  TUBES  AND   THE  X-RAYS  49 

Instead  of  the  movable  arm,  a  terminal  tape  and  a  third  terminal 
on  the  coil  may  be  used.  (Fig.  45.)  Thus  the  tube-regulating  spark  is 
transferred  from  the  tube  to  the  coil.  The  hitching  of  a  tube  to  a  coil 
with  a  third  terminal  is  very  simple.  Hitch  the  positive  terminal  to  the 
anode,  or  assistant  anode  if  desired,  and  the  negative  terminal  to  the 
cathode,  as  usual ;  and  the  third  terminal  to  the  regulating  chamber.  The 
advantages  of  the  third  terminal  over  the  movable  arm  are  that  the  spark- 
ing is  taken  away  from  the  tube  and  so  away  from  the  patient  (in  radio- 
graphic work  the  tube  is  always  near  the  patient),  and,  on  some  coils, 
Fig.  13  for  example,  the  gap  may  be  regulated  from  the  end  of  the  coil 
where  the  rheostat  and  switches  are  located,  so  making  it  unnecessary 
for  the  operator  to  move  from  his  position  to  change  the  tube-regulating 
spark  gap. 

When  the  current  passes  from  anode  to  cathode,  the  cathode 
stream  (Fig.  46)  is  given  off  from  the  cathode.  The  cathode  stream 
is  a  form  of  vibratory  motion  of  the  ether.  Leaving  the  concave  surface 
of  the  cathode,  the  cathode  stream  is  focused  to  strike  the  anode  or  target 
at  a  point.  X-rays  are  given  off  from  this  point  (Fig.  46).  The  cathode 
stream  can  be  seen  in  a  tube  of  very  low  vacuum,  appearing  blue. 

Great  heat  is  generated  at  the  point  on  the  target  where  the 
cathode  stream  strikes  it.  Hence  the  necessity  of  making  the  target  of 
some  very  high  fusing  metal.  A  small  hole  may  be  burned  superficially 
into  the  target  without  spoiling  the  tube.  The  tube  in  Fig.  47  has  a 
long  sheath  of  metal  connected  with  the  target  to  take  up  the  heat.  Tubes 
are  made  with  a  means  for  cooling  with  water.  These  are  intended  for 
treatment  rather  than  picture  work,  though  they  may  be  used  for  the 
latter. 

X-rays  were  discovered  by  William  Conrad  Roentgen,  professor  of 
physics'"  at  the  Royal  University  of  Wurzburg,  Germany,  in  the  summer 
of  1895.  Roentgen  applied  the  name  X-rays  because  he  did  not  know 
just  what  he  had  discovered ;  X,  the  algebraic  symbol  for  the  unknown, 
being  adopted  to  signify  this  ignorance.  They  were  not  called  X-rays 
because  the  rays  cross,  forming  an  X,  as  is  popularly  supposed. 

The  Roentgen  Congress,  in  Berlin,  1905,  adopted  a  uniform  set  ot 
technical  terms  in  which  the  word  Roentgen  always  occurred.  Thus  we 
have  the  phrase  Roentgen  ray  for  X-ray  and  such  words  as  Roentgen- 
ology, Roentgenologists,  Roentgenogram,  etc.,  etc.  While  approving  of 
a  move  for  a  uniform  nomenclature,  many  of  the  new  words  are  long 
and  unwieldy  and  the  writer  shall,  in  this  work,  use  many  of  the  old  and 
better-known  terms. 

X-rays  are  mvisible,  vibratory  waves  of  or  in  the  ether.     The  most 


so 


ELEMENTARY  RADIOGRAPHY 


popular  theory  is  that  they  are  hght  waves  with  an  inconceivably  rapid 
rate  of  vibration.  Red  light  rays  vibrate  at  the  rate  of  four  hundred 
billion  per  second;  violet  rays  vibrate  at  the  rate  of  seven  hundred  and 


Fig.   47.      X-ray   tube    properly  lit   up. 


Fig. 


X-ray    tube    with    the    current    passing    through    it    in    the    wrong    direction. 


fifty  billion  per  second.     The  intermediate  colors — blue,  green,  yellow  and 
orange — vibrate  at  intermediate  degrees  of  rapidity. 

Though  human  vision  is  limited  to  about  three  hundred  and  fifty 
billion  variance,  the  difference  between  four  hundred  billion  and  seven 
hundred  and  fifty  billion,  may  we  not  fairly  assume  that  there  are  light 


X-RAY  TUBES  AND   THE  X-RAYS  51 

rays  of  a  higher  and  lower  vibration  invisible  to  us?  Ultra-violet  rays 
have  a  more  rapid  vibration  than  violet  rays,  and  have  no  action  on  the 
retina,  and  are  therefore  invisible.  X-rays  vibrate  more  rapidly  than 
ultra-violet  rays.  The  rapidity  of  their  vibration  is  estimated  at  288,- 
224,000,000,000,000*  (two  hundred  and  eighty-eight  quadrillions,  two 
hundred  and  twenty-four  trillions — French  notation)   per  second. 


Fig.    49.      The    inverse   spark   gap    on   the    left    is    open,    on    the   right   is    closed. 


As  just  mentioned  X-rays  are  invisible ;  in  fact,  they  are  not  discerni- 
ble to  any  of  the  special  senses.  They  pass  from  the  focal  point  on  the 
target  in  regular,  diverging  lines  (Fig.  46).  When  they  strike  an  object 
they  are  absorbed  by  it  or  pass  through  it.  Broadly  speaking,  it  may  be 
said  they  penetrate  objects  inversely,  according  to  the  density  of  the  ob- 
ject. They  cannot  be  refracted  or  condensed,  and  the  fact  that  they  can 
be  reflected  is  of  academic  interest  only  since  they  are  not  reflected  except 
under  what  I  should  call  experimental  conditions. 

The  passing  of  the  X-rays  through  the  glass  of  the  tube  gives  rise 
to  a  green  fluorescence  (green  light)  in  the  active  hemisphere — the  hemi- 
sphere in  front  of  the  target — of  the  tube.  Whether  a  tube  is  working 
well  or  not  can  be  determined  by  this  fluorescence.  There  should  be  a 
definite  line  of  demarcation  between  the  active  and  inactive  hemispheres 
of  the  tube.  A  tube  working  properly  should  light  up  as  per  Fig.  47. 
The  light  is  never  quite  steady;  it  wavers  a  little.  High,  medium  and 
low  tubes  give  slightly  difi^erent  fluorescences  when  in  operation.  The 
fluorescence  from  a  high  tube  is  a  very  light  yellowish  green ;  from  a  low 


duster's   "Dental   Electricity 


52 


ELEMENTARY  RADIOGRAPHY 


tube  a  bluish  green  and  from  a  medium  tube  an  intermediate  shade  of 


green. 


Just  here  let  it  be  said  that  an  exact  colored  picture  of  an  X-ray 
tube  in  operation  has  never  been  made.  I  obtained  the  services  of  an 
artist  and  spent  a  great  many  hours  on  the  work,  but  was  unable  to  make 
a  picture  worthy  of   reproduction.     The  light   from   an   X-ray   tube   in 


Fig.    50.       Patent    series    or    inverse    spark    .gap    for    positive    terminal. 


operation  is  of  a  peculiar  brilliancy  that  cannot  be  reproduced  in  crayons, 
water-colors,  or  ink. 

When  the  vacuum  of  a  tube  is  so  low  as  to  render  it  useless  for  radio- 
graphic purposes,  a  definite  blue  color  can  be  seen  here  and  there  in  the 
tube,  the  cathode  stream  can  sometimes  be  seen  appearing  blue,  and  the 
line  of  demarcation  between  the  active  and  inactive  hemispheres  of  the 
tube  is  not  well  defined. 

When  a  tube  is  punctured  the  vacuum  gets  very  low,  of  course,  and 
its  appearance  in  operation  may  be  as  just  described,  or,  as  sometimes 
occurs,  it  gives  rise  to  a  fluorescence  as  variegated  as  a  rainbow,  or  it  may 
not  light  at  all.  A  punctured  tube  can  sometimes  be  repaired  by  the 
manufacturer. 

When  the  vacuum  of  a  tube  is  too  high,  the  tube  lights  up  reluctantly 
a  very  yellowish  green,  and  the  line  of  demarcation  is  not  at  all  distinct. 

Fig.  48  illustrates  fairly  well  the  appearance  of  a  tube  with  the 
current  passing  through  it  in  the  wrong  direction.  When  this  condition 
is  seen  the  current  must  be  turned  ofif  quickly,  or  the  tube  will  be  ruined. 
Sometimes,  when  the  tube  is  properly  hitched  to  the  coil,  light  rings  back 
of  the  target,  similar  to  those  shown  in   Fig.  48,  may  be  seen.     This 


X-RAY  TUBES  AND   THE  X-RAYS 


53 


signifies  that  the  coil  is  generating  considerable  inverse  current.  Recall 
that,  while  the  current  generated  by  the  induction  coil  is  practically  a 
unidirectional  one,  there  is  an  inverse  current  which  is  sometimes  strong 
enough  to  manifest  itself  as  just  mentioned,  especially  when  the  vacuum 
of  the  tube  is  low. 


Fig.    51.     A   triple   valve   tube. 

It  is  not  at  all  desirable  to  allow  inverse  current 
Cutting  Out  to  pass  through  a  tube,  for  it  gives  rise  to  a  scattering 
Inverse  generation  of  X-rays  which  interfere  with  the  making 

Current.  of  a  clear  X-ray  picture.    There  are  four  moderately 

satisfactory  means  of  preventing  the  passage  of  in- 
verse current  through  the  tube. 

The  first  and  simplest  means  of  eliminating  inverse  current  is  to  make 
what  we  shall  call  an  inverse  spark  gap.  (This  gap  is  usually  referred  to 
as  the  "  series  "  spark  gap  because  it  is  in  series  with  the  X-ray  tube.) 
The  word  series,  so  used,  is  a  technical,  electrical  term,  and  fails  to  ex- 
plain the  function  of  the  gap  as  well  as  inverse  spark  gap.  The  gap  can 
be  seen  between  the  positive  terminal  of  the  coil  and  the  standard  holding 
the  positive  terminal  tape  reel  (Fig.  49).  A  similar  gap  may  be  made 
on  the  negative  side.  This  gap  cuts  inverse  current  out  of  a  tube  by  in- 
creasing resistance  to  the  point  where  the  voltage  of  the  inverse  current 
is  not  sufficient  to  jump  the  gap.  Unless  it  is  needed  to  cut  out  "  inverse  " 
from  the  tube  there  should  be  no  inverse  spark  gap ;  the  gap  should  be 
closed  as  on  the  right,  the  negative,  side  of  Fig.  49. 

The  second  means  of  eliminating  "  inverse  "  is  by  the  use  of  the 
patent  spark  gap.  (Fig.  50.)  The  current  passes  easily  from  point  to 
disc,  but  reluctantly  from  disc  to  point.  Thus  this  series  spark  gap  may  be 
used  to  cut  out  inverse  current  from  a  tube,  with  the  points  toward  the 
positive  terminal  tape  and  the  points  away  from  the  negative  terminal 
tape.  Fig.  50  shows  the  point  toward  the  positive  terminal  tape.  They 
should  be  turned  in  the  opposite  direction  at  the  negative  terminal — away 
from  the  tape. 


54 


ELEMENTARY    RADIOGRAPHY 


The  third  means  of  cutting  the  inverse  current  out  of  an  X-ray  tube 
is  by  means  of  a  valve  tube.  (Fig.  51.)  The  valve,  or  Villard  tube,  is  a 
tube  of  low,  or,  as  it  is  often  called,  Geissler  vacuum — 1/1,000  to  3/1,000 
of  an  atmosphere — with  a  disc  electrode  and  a  spiral  electrode,  both  made 
of  aluminum.  The  exact  reason  for  its  action  is  not  known,  but  the  elec- 
tric current  cannot  travel  through  it  well  except  in  one  direction — from 


Fig.    52. 


A 


Fig.    53.      An    oscillimeter. 


disc  to  spiral.  Thus,  to  cut  out  inverse  current  the  disc  end  of  the  valve 
may  be  attached  to  the  positive  terminal  tape  of  the  coil,  and,  by  means 
of  a  piece  of  conducting  tape,  or  wire,  the  spiral  end  connected  with  the 
target  side  of  the  tube.  Or  the  disc  end  of  the  valve  may  be  attached,  with 
a  piece  of  conducting  tape,  to  the  cathode  side  of  the  tube  and  the  spiral 
end  of  the  valve  to  the  negative  terminal  tape  of  the  coil.  (Fig.  52.)  Fig. 
83  shows  a  valve  tube  built  into — i.  e.,  as  a  part  of — an  X-ray  tube. 

Tt  is  claimed  by  some  that  the  valve  tube  acts  only  as  an  additional 
resistance  to  the  flow  of  the  inverse  current,  cutting  it  out  of  the  X-ray 
tube  in  the  same  manner  that  the  inverse  spark  gaps  do. 

The  fourth  means  of  eliminating  "  inverse  "  from  tubes  is  by  what  is 
called  a  multiple  inductance  control  on  the  induction  coil.  By  means  of 
this  control,  which  is  found  only  on  the  more  expensive  coils,  the  output 
current  of  the  coil  may  be  raised  or  lowered  in  voltage.  If  "  inverse  "  is 
seen  in  the  tube  the  voltage  should  be  lowered. 


X-RAV  TUBES  AND   THE  X-RAYS 


55 


Oscillimetcr  .  ^^^  oscillimeter  or  oscilloscope   (Fig.  53)   is  a 

Geissler  vacuum  tube  by  means  of  which  inverse  cur- 
rent may  be  detected  when  the  X-ray  tube  is  covered  with  an  opaque 


Fig.    54.      The    Meyer    penetrometer. 


Fig.    55.      A    fluoroscope. 


shield.     (Fig.  64.)     I  have  never  felt  the  need  of  it,  though  I  have  used 
an  opaque  shield  over  my  tube. 

As  has  been  stated,  the  X-rays  are  not  discernible 
Demonstration  *-°  ^^y  °^  ^^^  special  senses.     Their  existence,  how- 

Of  X-Rays.  ever,  can  be  demonstrated  as  follows : 

Place  an  X-ray  tube  in  a  wooden  box  so  that 
when  the  current  is  sent  through  it  no  fluorescence  can  be  seen.     Excite 


56  ELEMENTARY  RADIOGRAPHY 

the  tube  in  a  dark  room  and  approach  it  with  some  object  coated  with 
calcium  tungstate  or  platino-barium  cyanide,  and  the  object  will  be  seen 
to  fluoresce  or  glow  something  like  phosphorus.  This  fluorescence  is 
due  to  the  action  of  the  X-rays  (which  penetrate  the  wood  of  the  box 
easily)  on  the  calcium  tungstate  or  platino-barium  cyanide.  Hence  the 
closer  the  object  to  the  tube  the  more  and  stronger  the  X-rays  which 
strike  it,  and  the  brighter  the  fluorescence. 


Power  of  X-rays  from  different  tubes  differ  in  power  of 

Penetration  penetration.     A  low  tube  gives  the  least  penetrating 

Of  X-Rays.  X-rays ;  then  comes  the  medium  tube,  while  the  X- 

rays  from  a  high  tube  are  the  most  penetrating. 

The  degree  of  penetration  may  be  determined  by  means  of  a  pene- 
trometer. (Fig.  54.)  This  particular  kind  of  a  penetrometer  consists  of 
two  small  fiat  pieces  of  wood  fastened  together,  with  a  sheet  of  lead  be- 
tween them.  Holes  are  made  through  both  wood  and  lead.  Into  these 
holes  are  placed  thin  metal  discs  which  just  fit  the  holes.  The  different 
holes  receive  different  numbers  of  discs. 

To  use  this  style  of  penetrometer  we  must  have  a  fiuoroscope.  A 
fluoroscope  (Fig.  55)  consists  of  a  light  proof  box,  tapered  and  made  to 
fit  over  the  eyes  at  one  end,  and  covered  at  the  other  end  with  pasteboard 
coated  with  calcium  tungstate  or  platino-barium  cyanide.  If  one  should 
look  into  the  fluoroscope  holding  it  toward  ordinary  light  nothing  could 
be  seen — one  would  look  into  perfect  darkness.  But  if  the  fluoroscope 
should  be  held  so  that  the  X-ray  struck  its  screen — i.  e.,  the  pastboard 
covered  with  calcium  tungstate  or  platino-barium  cyanide — it  would  be 
seen  to  fluoresce,  or  glow,  or  light  up. 

If  now  the  penetrometer  is  held  between  the  fiuoroscope  and  the 
source  of  the  X-rays  a  shadow  will  be  seen  on  the  screen,  because  the 
lead  in  the  penetrometer  is  opaque  to  X-rays.  Whether  the  X-rays  will 
penetrate  the  metal  in  the  holes  depends  on  how  much  metal  there  is  to 
penetrate  and  how  penetrating  the  X-rays  are.  Thus  the  more  penetrat- 
ing the  rays  the  more  holes  can  be  seen. 

There  are  a  great  many  different  kinds  of  penetrometers.  I  shall 
not  describe  them  here,  but  will  give  the  scale  of  the  two  most  popular, 
the  Benoist  and  the  Walter,  together  with  that  of  the  Meyer  (Fig.  54). 

Benoist.        Walter.         Meyei 

Soft,  or  low  tube i —  2  i  i —  2 

Medium 3—5  2—3  3—4 

Hard  or  high 6 — 12  4 — 6  5 — ^lO 


X-RAY  TUBES  AND   THE  X-RAYS 


57 


While  the  penetrometer  is  a  very  valuable  appliance,  it  is  far  from 
being  a  necessity  in  the  practice  of  dental  radiography. 

As  X-rays  pass  through  the  glass  of  the  tube 

Secondary  more  X-rays  are  generated.     These  are  known  as 

l^ays.  "secondary  rays."    They  are  short  and  feeble  and  do 

not  travel  parallel  with  the  direct  X-rays,  but  pass 


Fig.    56.      High-frequency    X-ray   tube. 


Fig.    57.      High-frequency    X-ray    tube. 


out  from  the  tube  in  every  direction  intersecting  the  direct  rays.  Second- 
ary rays  are  also  given  oil  from  any  object  which  X-rays  strike.  Thus, 
direct  rays  will  strike  a  wall ;  secondary  rays  are  given  off  from  the  wall 
and  strike  the  other  walls,  the  floor,  and  the  ceiling,  whereupon  a  new 
set  of  X-rays,  tertiary  rays,  are  produced.  When  the  tertiary  rays  strike 
an  object  still  another  set  of  X-rays  are  generated,  and  so  on,  each  new 
set  of  rays  being  much  shorter  and  weaker  than  the  former.  So  a  room 
in  which  an  X-ray  tube  is  excited  is  filled  with  X-rays — not  with  the 
direct  rays,  but  with  the  comparatively  feeble  and  inconsequential  sec- 
ondary, tertiary  and  other  subordinate  rays. 


58 


ELEMENTARY  RADIOGRAPHY 


Classification  of  X-ray  tubes  are  of   different  sizes.     The  bulb 

X-Kav  tubes  varies  in  diameter  from  five  to  eight  inches.     Thus 

JlCCOrdittd  to  %m,        ^e  have  the  five-inch  tube,  six-inch  tube,  and  so  on. 
The  six-inch  tube  is  about  right  for  dental  work. 

With  use  the  glass  of  the  active  hemisphere  of  the  tube  discolors  to 
a  purplish  color.     This  does  not  materially  affect  the  tube. 

The  fatal  injury  to  most  tubes  is  a  puncture.     One  means  of  guard- 
ing against  punctures  is  to  keep  the  tube  clean.     "A  fruitful  cause  of 


Fig.    58.      Tube   rack    for   tubes   when    not   in   use. 


puncture  is  the  discharging  of  the  current  from  the  tube  into  the  rack  on 
which  the  tube  is  kept  when  not  in  use.  The  tube  may  have  been  dis- 
charged by  the  operator  touching  the  terminals  before  putting  the  tube 
away,  but  if  the  tubes  are  stored  in  the  same  room  where  high-frequency 
and  other  coil  discharges  are  taking  place,  they  will  recharge  themselves 
from  the  atmosphere  and  discharge  onto  the  rack,  no  matter  of  what 
material  the  rack  may  be  made.  A  safe  way  of  putting  away  tubes  is  to 
connect  the  anode  and  cathode  terminals  together  by  a  wire  during  the 
time  the  tube  is  at  rest." 

The    general    principle    of    construction    of    the 

Rigb-Trcqucncy  high-frequency  X-ray  tube    (Figs.   56  and   57)    are 

X-Ray  Cube,  those  already  given  in  the  description  of  the  tubes 

built  to  be  operated  by  a  unidirectional  current.    The 


X-RAY  TUBES  AND  THE  X-RAYS 


59 


chief  difference  between  the  high-frequency  tubes  and  those  already  de- 
scribed lies  in  the  different  means  resorted  to  in  the  former  to  dispose  of 
one  direction  or  wave  of  the  alternating  current,  or,  to  speak  more  def- 
initely, one  cathode  stream. 


Fig.   59.  Fig.   60. 

Fig.  59.     Plain  X-ray  tube  stand. 
Fig.   60.      Tube  stand,  with  a  lead  glass  protection  shield  and  a  compression  cone. 


Either  end  of  a  high-frequency  X-ray  tube  may  be  connected  with 
either  terminal  tape  of  a  high-frequency  coil.  While  this  is  theoretically 
true,  it  will  sometimes  be  found  in  practice  that  the  tube  works  better 
hitched  up  one  way  than  the  other. 

When  the  tube  is  hitched  up  the  current  oscillates  through  it  and 
two  cathode  streams  are  generated.  One  of  the  streams  is  focussed 
against  the  target  and  X-rays  are  given  off  from  the  focal  point,  while 


6o 


ELEMENTARY  RADIOGRAPHY 


the  other  is  focused  into  a  funnel  in  the  back  of  the  target.  (Fig.  56.) 
X-rays  cannot  be  given  off  from  this  funnel;  hence  the  tube  lights  up  in 
the  active  hemisphere  as  illustrated  in  Fig.  47.     This  funnel  scheme  is 


Fig.  61.     \  pedestal,  with  a  lead  glass  protection  shield,  compression  cone  and  plate  holder. 


one  way  of  taking  care  of  one  cathode  stream  while  the  other  is  being 
used  for  X-ray  production.  Another  scheme  is  to  move  one  cathode  back 
so  far  that  the  cathode  stream  focuses  before  reaching  the  back  of  the 
target.      (Fig.  57.) 

The  high-frequency  tube  may  be  used  to  advantage  on  an  induction 
coil  which  is  generating  a  great  deal  of  inverse  current. 

The  transformer  tube  is  almost  identical  in  con- 

transformcr  struction  with  the  induction  coil  tube.    It  is,  however, 

X-Ray  tubes  made  to  take  a  current  higher  in  milliamperage  and 

lower  in  voltage;  that  is,  the  target  is  thicker  and 

the  metax  sheath  leading  from  it  heavier  to  take  up  the  heat  due  to  the  use 

of  the  high  milliamperage,  and  the  vacuum  is  normally  a  little  lower. 


X-RAY    TUBES   AND    THE    X-RAYS 


6i 


To  avoid  "  straining  "  a  tube,  it  should  not  be  used  again,  after  hav- 
ing been  used  till  hot,  until  it  has  cooled  thoroughly.  Overheating  the 
tube  will  destroy  the  gases  in  it,  and  so  raise  the  vacuum  to  such  a  degree 
as  to  make  it  impossible  to  force  a  sufficient  milliamperage  through  it  to 
produce  a  sufficient  number  of  X-rays.     Sending  a  very  strong  current 


Table,    with    a    lead    glass    protection    shield    and    compression    cylinder. 

through  a  tube  of  low  vacuum  will  also  destroy  the  gases  of  the  tube  and 
spoil — strain — it. 

Fig.  58  is  a  tube  rack  for  holding  the  tube  when  not  m  use. 

It  is  obvious  that  there  must  be  some  kind  of  a  device  for  holding 
the  tube  when  in  use.  This  may  be  either  a  plain  tube  stand  (Fig.  59), 
or  a  tube  stand  with  a  lead  glass,  protection  shield  and  a  compression 


62 


ELEMENTARY  RADIOGRAPHY 


X-RAY  TUBES  AND  THE  X-RAYS 


63 


cone  (Fig.  60),  or  a  pedestal  with  a  lead  glass  protection  shield,  compres- 
sion cone,  and  plate  holder  (Fig.  61),  ora  table  with  a  lead  glass,  protec- 
tion shield  and  compression  cylinder.     (Fig.  62.) 

Dr.  Blum,  of  New  York,  uses  a  wall  bracket  fixture  to  support  a 
lead  glass,  protection  shield  and  compression  cylinder.  The  tube,  one 
of    the    water-cooled    type,    is    seen    fitting    into    the    lead    glass    shield. 


Fig.    64.       A    Protection    Shield. 


(Fig.  63.)  This  would  be,  I  imagine,  a  very  adaptable  and  satisfactory 
apparatus. 

A  tube  stand  should  be  heavy  enough  to  be  firm  and  not  allow  any 
vibration  of  the  tube  while  in  use.  The  parts  coming  in  contact  with  the 
tube  must  be  made  of  an  electric  non-conducting  material ;  otherwise  the 
current  would  pass  from  the  tube  into  them,  so  puncturing  the  tube. 

The  uses  of  the  compression  cone  or  cylinder  are :  (i)  To  cut  out  sec- 
ondary and  inverse  current  rays  (Fig.  65).  (2)  To  aid  the  operator  in 
directing  the  X-rays  at  the  correct  angle.  (3)  In  general  radiography,  to 
hold  the  patient  immovable  and  compress  the  soft  parts  as  when  making 
a  picture  of  the  kidney,  for  example. 

A  protection  shield,  often  called  a  Friedlander's  shield  (Fig.  64), 
which  is  opaque  to  X-rays  except  for  the  window  or  opening  in  it,  and 
which  is  used  to  cover  X-ray  tubes,  also  cuts  out  some,  but  not  all,  second- 
ary rays  given  off  from  the  glass  of  the  tube.    Thus  if  the  X-rays  from  an 


64 


ELEMENTARY  RADIOGRAPHY 


X-ray  tube  are  directed  on  a  part  through  a  diaphragm  and  cone  or  cylin- 
der, only  the  direct  rays  strike  the  part,  as  in  the  diagram  study  shown  in 
Fig.  65.     While,  with  the  Friedlander  shield,  some  of  the  secondary  rays 


Fig.    65.     D    D    D,    direct    ray.       S    S,    secondary    ray.      P    P,    part. 


Fig.   66.     D   D   D,   direct   rays.      S    S,   secondary   rays.      P   P,  part. 


might  strike  the  part  also.  (Fig.  66.)  The  diaphragm  is  a  piece  of  lead 
with  a  hole  in  it,  situated,  as  a  removable  part  of  the  tube  stand,  between 
the  X-ray  tube  and  the  cone,  cylinder,  or  square.     (Fig.  328.) 


CHAPTER    IV. 
making  Radiographs. 

The  X-ray  picture  is  variously  called  radiograph,  skiagraph,  Roent- 
genograph, radiogram,  skiagram  and  Roentgenogram.  The  word  radi- 
ograph is  a  combination  of  a  Latin  and  Greek  word  meaning  ray  and 
write  or  record.  The  word  skiagraph  (spelled  also  sciagraph)  is  a  com- 
bination of  two  Greek  words  meaning  shade  or  shadow  and  write  or  re- 
cord. The  word  Roentgenograph  is  a  combination  of  a  proper  name. 
Roentgen,  and  the  Greek  word  meaning  write  or  record.  The  terminal 
gram  occurring  in  the  words  radiogram,  skiagram  and  Roentgenogram 
— as  well  as  the  more  common  words  such  as  telegram,  program,  epi- 
gram, and  others — is  of  Greek  origin  and  denotes  that  which  is  written 
or  marked. 

The  use  of  the  X-rays  for  radiographic  work  depends  on  two  prop- 
erties of  the  rays.  First,  they  penetrate  substances  in  direct  proportion 
to  the  density  of  the  substance,  and  second,  they  affect  the  photographic 
plate  or  film  the  same  as  white  light  does. 

A  photographic  plate  is  a  piece  of  transparent 

PbOtOgrapbiC  plate  glass   about  an  eighth  of  an  inch  thick,  one 

Plates,  side    of    which    is    coated    with    an    emulsion    of 

a  silver  salt,  usually  silver  bromide,  and  gela- 
tine, albumen,  or  collodion.  The  use  of  the  gelatine,  albumen  or 
collodion  is  simply  to  stick  the  salt  to  the  glass.  When  a  thin 
coating  of  this  emulsion  has  dried  on  the  glass  we  have  what  is 
called  the  photographic  "dry  plate."  In  appearance  it  is  similar  to  trans- 
lucent greenish-white  glass,  but  on  close  inspection  one  is  able  to  de- 
tect that  one  side  is  a  little  less  glossy  than  the  other.  The  less  glossy 
is  the  coated  side,  also  called  the  sensitive,  the  film,  or  the  emulsion  side 
of  the  plate.  The  term  "dry  plate"  is  to-day  an  almost  superfluous  one, 
practically  all  the  plates  used  being  dry  plates.  There  is,  however,  a 
photographic  plate  known  as  the  "wet  plate,"  but,  since  it  is  never  used 
in  radiography,  I  shall  not  describe  it. 

65 


66  ELEMENTARY   RADIOGRAPHY 

The  dry  plate  is  made  in  the  absence  of  white  light,  put  up  in  light- 
proof  packages,  and  so  supplied  to  consumers.  These  packages  must  not 
be  opened  except  in  a  dark  room,  for  the  slightest  exposure  to  a  white 
light  will  spoil  them. 

-  The  difference  between  the  photographic  dry  plate  and  the  photo- 
graphic film  is  only  that  the  plate  is  a  piece  of  glass  coated  with  a 
silver  salt,  while  the  film  is  a  thin  sheet  of  transparent  celluloid  coated 
with  a  silver  salt.  As  with  the  plate,  the  sensitive  side  of  the  film  is  a 
little  less  glossy  than  the  uncoated  side.  The  film  curls  slightly  toward 
the  coated  side,  unless  it  is  of  the  "non-curling"  variety,  when  it  is 
straight,  or  may  even  curl  slightly  away  from  the  coated  side.  One 
method  of  making  non-curling  films  is  to  coat  the  non-sensitive  side  with 
gelatin  without  any  silver  incorporated  in  it. 

X-ray  pictures  may  be  made  on  ordinary  plates 
Special  and  films  made  to  be  used  in  cameras.     While  this 

X-tay  Plates  may  be   done,  the  results  obtained  are   usually  not 

and  films  nearly   so   good   as   when   special   X-ray   plates   and 

films  are  used.  Special  X-ray  plates  and  films  are 
extremely  sensitive — that  is,  easily  acted  upon  by  light — for,  though  the 
X-rays  have  a  wonderful  power  of  penetration,  their  action  on  the  silver 
emulsion  of  the  photographic  plate  is  feeble  compared  to  the  white  light 
of  day.  To  make  them  especially  susceptible  to  the  action  of  the  X-rays 
some  X-ray  plates  contain  some  fluorescent  substance  in  the  silver  emul- 
sion. Multi-coated  plates  are  plates  which  have  been  coated  with  more 
than  one  coating  of  emulsion,  one  coat  on  another. 

Special  X-ray  plates  and  films  can  be  obtained  from  many  photo- 
graphic supply  houses  and  from  any  X-ray  equipment  company.  The 
following  is  a  list  of  the  manufacturers  who  make  special  X-ray  plates : 
George  W.  Brady  &  Co.,  Chicago,  111. ;  the  Eastman  Kodak  Co.  and  the 
Forbes  Dry  Plate  Co.,  Rochester,  N.  Y. ;  Cramer  Dry  Plate  Co.,  St.  Louis, 
Mo. ;  the  Hammer  Dry  Plate  Co.,  St.  Louis,  Mo. ;  the  Lumiere  N.  A. 
Co.,  New  York  City,  and  the  Ilford  Mfg.  Co.,  London,  England.  So  far 
as  I  am  able  to  learn  only  two  manufacturers  make  X-ray  films:  The 
Eastman  Kodak  Co.  and  the  Ilford  Mfg.  Co.  Since  the  war  it  has  been 
difficult  to  obtain  the  Ilford  film.  A  German  film,  the  Schleussner  film, 
can  no  longer  be  obtained  at  all  on  account  of  the  war. 

I  wish  here  to  advise  against  buying  large  quantities  of  either  plates 
or  films  at  a  time.     They  deteriorate  in  a  few  months. 

The  making  of  a  radiograph  of  the  hand  is  one 
CCCbniC  of  of  the  simplest  operations  in  radiography,   and  for 

ItlaKiltd  that  reason  it  will  be  described  to  teach  elementary 

Radiographs  principles.    The  following  technic  of  making  a  radio- 

graph will,   of   necessity,   be   much  broken   into  by 
descriptions  of  materials  and  appliances  used. 

A  5  X  7-inch  plate  is  about  the  right  size  to  make  a  radiograph  of 


MAKING  RADIOGRAPHS 


67 


the  hand.  Plates  are  supplied  by  the  manufacturer  packed  in  light-proof 
boxes,  holding  usually  one  dozen  plates,  with  the  warning  on  the  box. 
"Open  only  in  a  dark  room."  The  "dark  room"  is  simply  what  the  name 
states — a  room  from  which  light  is  excluded.  A  closet  without  a  window 
makes  a  good  dark  room,  except  that  there  is  seldom  running  water  in  it. 
It  is  not  absolutely  necessary  to  have  running  water  in  the  dark  room, 
but  it  is  very  convenient.     If  a  closet  cannot  be  utilized  a  room,  light- 


sr/f/f> 
Fig.   67.      To   left,   window   ready   for   frame.      When   frame   is   in    position   the   metal    catches   are 
turned  to  hold  it.     The  frame  fits  inside  of  the  strip  on  the  sill.     Figure  to  right  shows 

frame    in    position. 


proof  except  for  one  window,  may  be  made  dark  by  covering  the  window 
with  a  frame  on  which  is  tacked  some  material  such  as  the  leather  or 
rubber  used  for  side  and  storm  curtains  in  buggies.  If  this  material  does 
not  completely  turn  the  light,  it  should  be  painted  with  thick  black  paint. 
The  frame  should  be  made  to  fit  over,  not  into,  the  window  casing.  (Fig. 
67.)  With  the  frame  so  placed,  if  a  little  light  comes  in  around  it,  it 
does  not  come  directly  into  the  room,  but  is  reflected  to  the  side.  The 
more  perfect  the  darkness  of  the  room  the  better,  but  the  very  little  light 


68 


ELEMENTARY  RADIOGRAPHY 


which  can  enter  through  a  window  with  the  bHnd  drawn  down,  and  with 
a  well-made  frame  over  it  will  not  cause  any  trouble.  If  the  door  to  the 
room  permits  light  to  leak  in  around  it,  such  light  should  also  be  shut  out. 
It  would  be  impossible,  of  course,  to  work  to  any  advantage  in  a 
perfectly  dark  room,  for  we  could  not  see  what  we  were  doing..  Hence 
the  necessity  of  having  a  dark  room  lantern  (Fig.  68),  which  will  give 
sufficient  light  to  guide  us  in  our  work,  without  being  of  such  nature  as 
to  have  any  action  on  plates  or  films.    The  term  "developing  light" — the 


Fig.   68.     Dark   room  lantern. 


light  given  by  the  dark  room  lantern — may  mislead  one  to  believe  that 
the  light  in  some  way  aids  in  developing  a  plate  by  its  action  on  it.  But 
such  is  not  the  case.  The  light  is  of  value  only  because  it  enables  the 
worker  to  see.  The  light  may  be  a  candle,  a  coal  oil  lamp,  or  an  incan- 
descent electric  light  shining  through  red  glass.  While  such  a  lantern 
can  easily  be  made,  the  writer  warns  against  it,  for,  though  the  light  of  a 
home-made  lantern  may  appear  the  same  to  the  eye  as  the  light  of  the 
lanterns  manufactured  by  photographic  supply  manufacturers,  its  action 
on  a  plate  or  film  may  be  disastrously  dififerent.  The  lantern  shown  in 
Fig.  68  consists  of  a  i6-candle  power  incandescent  light  with  a  frosted 
glass  bulb,  in  a  light-proof  tin  box,  the  front  of  which  is  of  removable 
glass.  The  light  shines  first  through  the  frosted  glass  of  the  bulb,  then 
an  orange-colored  glass,  then  a  ruby  glass. 

In  the  dark  room,  with  only  the  light  of  the  dark  room  lantern  we 


MAKING  RADIOGRAPHS 


69 


open  our  box  of  plates,*  take  out  one.  carefully  close  the  box,  and  place 
the  plate  in  an  envelope  of  black,  light-proof  paper  just  large  enough  to 
receive  it.  Now  place  plate,  black  envelope,  et  al.,  in  another  envelope 
of  black  or  orange-colored  paper,  putting  the  open  end  of  the  first  en- 
velope in  first.  We  may  now  expose  this  package  to  ordinary  daylight 
and  artificial  light  with  impunity,  and  the  plate  is  ready  for  use  in  the 
making  of  a  radiograph.  These  envelopes  are  obtained  from  the  plate 
manufacturers. 


Fig.    69.      Showing    how    to    handle    a    plate    by    its    edges. 


While  in  the  dark  room,  before  putting  the  plate  in  the  envelope,  we 
must  note  which  is  the  sensitive  side,  and  bear  this  in  mind  until  the 
outside  envelope  is  marked  properly  to  designate  it.  As  formerly  stated, 
the  sensitive  side  is  a  little  less  glossy.  Another  way  to  determine  which 
is  the  coated  side  is  to  look  through  the  plate  just  at  the  edge.  When 
the  glass  side  is  up,  one  is  able  to  look  through  the  glass  and  see  the  film 
beneath.  The  sensitive  side  of  the  plate  should  present  toward  the 
smooth  side  of  the  envelope — away  from  the  seam  side. 

The  plate  should  be  handled  by  the  edges.  (Fig.  69.)  This  applies 
to  the  handling  of  the  plate  at  all  times,  and  to  the  handling  of  the  film 
as  well.    Unless  the  fingers  are  wet  or  greasy,  touching  the  sensitive  side 


*Experienced  photographers  prefer  to  handle  sensitive  plates  in  absolute  dark- 
ness, and  soon  learn  to  detect  the  film  side  of  the  plate  bj'  feehng  hghtly  with  the 
fingers,  thus  obviating  the  need  of  the  dark  room  light  when  "loading"  plates. — Ed. 


70 


ELEMENTARY  RADIOGRAPHY 


of  the  plate  is  not  likely  to  result  in  spotting  the  picture,  but  it  is  always 
well  to  eliminate  as  many  chances  of  failure  as  possible. 

We  are  now  ready  to  arrange  tube,  hand,  and  plate  in  their  proper 
relative  positions  to  take  the  picture.     In  all  radiographic  work  it  must 


STA/^D 


Fig.  70.  Showing  relative  positions  of  tube,  hand,  and  plate  for  making  a  radiograph  of  the  hand. 


constantly  be  borne  in  mind  that  we  are  making  a  shadow  picture;  that 
we  are  simply  throwing  a  shadow  on  the  plate,  using  X-rays  as  the 
source  of  light. 

Lay  the  plate  on  a  stand,  sensitive  side  up.  Place  the  hand  on  the 
plate.  Adjust  the  tube  at  a  variable  distance  directly  above  the  hand, 
(Fig.  70.) 


MAKING  RADIOGRAPHS  7^ 

The  distance  from  the  tube  to  the  plate  may  vary  from  about  lo  to 
20  inches,  measurements  being  taken  from  the  target,  not  from  the  glass 
of  the  tube.  It  is  not  necessary  to  have  the  target  and  the  plate  parahel 
to  one  another  (in  the  same  plane)  as  some  writers  direct.  On  the  con- 
trary, the  position  as  in  Fig.  70   is  a  better  arrangement. 

Assuming  now  that  the  tube  is  properly  hitched  to  the  coil  and  work- 
ing properly,  we  are  ready  to  make  the  exposure — to  take  the  picture. 

In  giving  demonstrations,  I  find  that  at  this  point  someone  invariably 
volunteers  to  "turn  out  the  light."  This  is  not  necessary.  The  only 
reason  for  having  the  rooms  even  slightly  darkened  is  to  enable  the  ope- 
rator to  observe  how  his  tube  is  working.  The  picture  could  be  taken  in 
bright  daylight ;  the  envelopes  will  protect  the  plate  against  all  light  ex- 
cept the  X-rays.     (See  Chapter  V  for  technic  of  lighting  X-ray  tube.) 

When  the  switch  is  turned  on  and  the  X-rays  produced,  they,  the 
rays,  shine  down  on  the  plate  penetrating  the  paper  of  the  envelopes  as 
though  the  plate  were  not  covered  at  all.  The  rays  penetrate  the  hand 
also  and  act  upon  the  plate  beneath.  They  penetrate  the  bones  of  the 
hand  less  readily  than  the  flesh,  and  hence  there  is  less  action  on  the 
plate  directly  beneath  the  bones.  In  other  words,  there  is  a  shadow  of 
the  hand  thrown  on  the  plate,  the  shadow  of  the  bones  being  denser  than 
the  shadow  of  the  flesh.  The  shadow  of  the  flesh,  in  fact,  may  be  so 
light  that  it  is  scarcely  discernible,  or  even  entirely  blotted  out.  This  is 
the  case  when  a  very  high  tube  is  used  and  a  long  exposure  made. 

The  length  of  time  of  the  exposure  of  the  plate 
Duration  of  to  the  action  of  the  X-rays  when  making  a  radio- 

€xpO$urc.  graph  depends  on  several  things,     (i)  The  milliam- 

perage  sent  through  the  tube.  Other  factors  re- 
maining the  same,  the  more  milliamperage  sent  through  the  tube  the 
shorter  the  exposure  necessary,  because  the  higher  the  milliamperage 
sent  through  the  tube  the  greater  the  number  of  X-rays  produced. 
A  coil  equipped  with  a  milliamperemeter  enables  the  operator  to 
observe  the  exact  number  of  milliamperes  passing  through  the  tube. 
(2)  The  nature  of  the  X-rays.  Other  factors  remaining  the  same, 
the  more  penetrating  the  X-rays  the  shorter  the  exposure  necessary. 
The  higher  the  vacuum  of  the  tube  up  to  a  given  point,  the  more 
penetrating  the  rays  from  it.  A  low  tube  is  useless  for  radiographic 
work.  (3)  The  distance  of  the  plate  from  the  tube.  Other  factors 
remaining  the  same,  the  shorter  the  distance  between  the  plate  and 
the  tube  the  shorter  the  exposure  necessary.  (4)  The  thickness  of  the 
part  to  be  radiographed.  Other  factors  remaining  the  same,  the  thicker 
the  part  the  longer  the  exposure  necessary.     (5)  The  density  of  the  part 


72 


ELEMENTARY  RADIOGRAPHY 


to  be  radiographed.  Other  factors  remaining  the  same,  the  denser  the 
part  the  longer  the  exposure  necessary.  (6)  The  sensitiveness  of  the 
plate.  Other  factors  remaining  the  same,  the  more  sensitive  the  plate 
the  shorter  the  exposure  necessary.  The  product  of  some  manufacturers 
is  more  sensitive  than  others.  As  a  plate  or  film  grows  old  it  becomes 
less  sensitive,  finally  becoming  entirely  useless. 


Fig.  71.     Radiograph  of  the  hand,  made  from  a  pose  similar  to  Fig.  70.     (Reduced  one-half.) 


It  will  be  seen  from  the  foregoing  that  so  many  things  enter  in  for 
consideration  that  the  exact  time  of  exposure  cannot  be  stated  with  any 
degree  of  clearness.  Elaborate  systems  of  calculation  have  been  worked 
out  so  that  if  the  distance  of  the  tube  from  the  plate,  the  penetration  of 
the  X-rays  measured  with  a  penetrometer,  the  milliamperage  sent  through 
the  tube,  and  the  thickness  of  the  part  be  known,  reference  can  be  made 
to  a  printed  table  and  the  exact  time  of  exposure  necessary  learned. 
While  commending  such  work  as  efiforts  along  the  right  line,  I  consider 
them  failures  so  far  as  practical  application  in  dental  work  is  concerned. 
Notice  that  in  the  calculation  the  density  of  the  part  and  sensitiveness  of 
the  plate  are  not  taken  into  account  at  all. 


MAKING    RADIOGRAPHS  73 

Each  man  must  learn  to  properly  time  his  exposure  by  personal  ex- 
perimentation. This  statement  is  likely  to  be  contradicted  by  those  who 
construe  it  to  mean  that  no  idea  at  all  of  the  time  of  the  exposure  can 
be  learned  except  by  experiment.  That  is  not  what  I  am  saying,  however. 
The  idea  I  wish  to  convey  is  that  these  tables  of  calculation,  on  the  time 
of  exposure,  give  only  the  approximate  length  of  time  necessary,  and  that 
a  very  little  experience  and  the  use  of  judgment  render  them  useless. 
They  are  always  useless  except  when  a  penetrometer  is  used  and  the  coil 
is  equipped  with  a  milliammeter. 


Fig.   72.      Trays  for   developing  and   fixing  solution 

To  make  a  negative  (the  picture  on  the  glass  of  the  plate)  like  the 
radiograph  shown  in  Fig.  yi,  the  factors  may  be  as  follows: 

1.  Machine  used:  A  large  induction  coil,  with  a  two-point  elec- 
trolytic interrupter,  operating  on  iio-volt,  D.C.  circuit.  Three-fourths  of 
the  resistance  of  rheostat  cut  out. 

2.  Strength  of  current :  Machine  not  equipped  with  ammeter  or 
milliammeter.  Approximate  amperage  of  the  primary  current,  20.  Sec- 
ondary current  sufficiently  powerful  to  obtain  a  fat,  fuzzy  spark  10  inches 
long — an  estimate,  about  10  milliamperes. 

3.  Penetration  of  X-rays :  Tube  backs  up  5  inches  of  parallel  spark. 
Distance  of  tube  regulating  spark  gap  5  inches.  Therefore,  the  tube  is 
medium  high  and  the  rays  from  it  rather  penetrating  when  it  is  properly 
lighted.     Benoist  penetrometer  5. 

4.  Distance  of  target  from  plate:  Twenty  (20)  inches. 

5.  Thickness  of  part:  That  of  hand,  about  i/^  inches  at  thickest 
part. 

6.  Density  of  part :  That  of  hand. 

7.  Plate  used :  Paragon  special  X-ray  plate.  (An  ordinary  camera 
photographic  plate  might  have  been  used  to  take  such  a  picture.  Had  this 
been  done,  however,  the  time  of  exposure  necessary  would  have  been 
about  twice  as  long.) 

8.  Time  of  exposure  of  plate  to  action  of  rays  :  Two  (2)  seconds. 

9.  Time  plate  remained  in  developer :  Five  minutes. 


74  ELEMENTARY   RADIOGRAPHY 

During  exposure,  the  patient,  tube  and  plate  must  be  perfectly  immo- 
bile.   After  the  exposure  we  are  ready  to  "  develop  the  negative." 

Remove  the  plate  from  the  envelope  in  the  dark 

method  of  room,  exposing  it  only  to  the  ruby  light.     It  has  not 

Development.  changed  in  appearance  at  all.     It  still  looks  like  a 

piece  of  translucent,  white  glass.  But  the  picture  is 
there.    It  needs  only  to  be  developed. 

This  is  done  by  immersing  the  plate,  sensitive  side  up,  in  an  aqueous 
solution  of  chemicals,  the  developer.  This  developer  causes  that  part  of 
the  plate  which  has  been  acted  upon  by  the  X-rays  to  turn  dark,  but  does 
not  cause  that  part  of  the  plate  which  has  not  been  acted  upon  by  the  X- 
rays  to  turn  dark.  The  degree  of  darkness  produced  by  the  developer 
in  the  plate  varies  directly  according  to  the  extent  of  the  action  of  the  X- 
rays  on  the  plate. 

Place  the  plate  in  the  tray  (Fig.  72)  containing  the  developer  with 
the  coated  side  up,  quickly  covering  the  plate  with  the  solution.  A  conveni- 
ent way  to  make  certain  that  the  developing  solution  covers  all  of  the 
surface  of  the  plate  immediately  is  to  place  the  plate  in  the  empty  tray 
(sensitive  side  up  of  course)  and  pour  the  developer,  out  of  a  tumbler, 
over  it.  Expose  the  plate  to  even  the  light  of  the  dark  room  lantern  as 
little  as  possible  until  development  is  well  under  way.  Trays  can  be  pur- 
chased from  any  photographic  supply  house.  Always  use  a  tray  suffi- 
ciently large  to  easily  receive  the  plate.  The  action  of  the  developer  will 
be  hastened  and  made  more  uniformly  perfect  by  slightly  raising,  then 
lowering,  one  end  of  the  tray,  and  so  moving  the  developer  over  the  sur- 
face of  the  plate. 

The  length  of  time  it  takes  the  image  or  "  picture  "  to  "  come  up  "  or 
show  varies  according  to  the  length  of  exposure.  If  the  exposure  has 
been  well  timed  and  the  developer  used  acts  as  the  average  developer 
acts,  neither  very  rapidly  or  very  slowly,  the  image  will  appear  in  about 
30  seconds ;  if  the  exposure  has  been  a  little  overtimed,  the  image  may 
appear  in  about  10  or  15  seconds  ;  if  it  has  been  a  little  undertimed,  it  may 
take  I  or  2  minutes  for  the  image  to  appear. 

Developing  is  not  completed  as  soon  as  the  image  shows.  Sometimes 
the  image  can  be  seen  better  by  removing  the  plate  from  the  developer 
and  holding  it  up  to  the  ruby  light.  If  the  exposure  has  been  well  timed 
the  "  high  lights  "  will  commence  to  appear  (i.  e.,  the  plate  will  begin 
to  turn  dark  in  places)  in  about  15  seconds,  and,  as  just  stated,  the  image 
can  be  seen  tolerably  well  in  30  seconds.  If  this  is  the  case  the  plate 
should  be  left  in  the  developer  about  5  minutes.     From  the  foregoing  we 


MAKING  RADIOGRAPHS  75 

may  make  the  following  rule :  Leave  the  plate  in  the  developer  about  20 
times  as  long  as  it  takes  for  the  high  lights  to  appear,  or  10  times  as  long 
as  it  takes  for  the  image  to  appear.  This  is  not  an  inflexible  rule.  Indeed, 
no  inflexible  general  rule  can  be  made,  because  of  the  difference  in  the 
action  of  different  developers.  Another  rule  is  to  leave  the  plate  in  the 
developer  until  the  image  can  be  seen  on  the  glass  side  of  the  plate. 

The  actual  time  of  developing  will  vary:  2  or  3  minutes  for  over- 
timed exposures;  about  5  minutes  for  plates  which  have  been  well  ex- 
posed; 10  to  15  minutes  for  undertimed  exposures.  This  applies  to  most 
developing  solutions.  However,  developers  known  as  "  slow  "  developers 
require  about  20  minutes  for  well-exposed  plates,  and  the  Brady,  Paragon 
developer,  known  as  the  "  four-minute  developer,"  requires  only  4  min- 
utes. 

There  are  a  very  great  many  different  developing  formulas,  any  of 
which  may  be  used.  In  making  up  developers,  chemicals  should  invariably 
be  dissolved  in  the  order  as  named.  The  following  are  some  of  the  most 
popular  developer  formulas : 


M — Q  Developer  * 

Avoirdupois  Metric  System 

Water    10  ounces  =  300      c.c. 

Metol  7  grains  -^  i^  grammes 

Hydrochinon    30  grains  =  2      grammes 

Sulphite  of  Soda  (desiccated) no  grains  =  7      grammes 

Carbonate  of  Soda  (desiccated) 200  grains  =  13      grammes 

10  per  cent,  solution  Bromide  Potassium 40  drops    =  40      drops 

Hydrochinon   Developer 
No.   I 

Avoirdupois  Metric  System 

Hydrochinon 300  grains 20  grammes 

Sulphite  of  Soda 6  ounces 180  grammes 

Water    48  ounces 1,440  c.c. 

No.  2 

Carbonate  of   Potassium 4  ounces 120  grammes 

Water   32  ounces 960  c.c. 

To   Develop,   take 

No.   I,  6  ounces    (180  c.c.)  ;    No.  2,  4  ounces    (120  c.c.)  ;     10  per  cent,  solution 
Bromide  of  Potassium,  3  to  10  drops.     Mix. 


*M — Q  stands  for  "metal — quinol."  In  photography  the  word  "quinol"  is  used 
as  an  abbreviation  for  "hydroquinol."  This  is  unfortunate,  because  quinol  and 
hydroquinol  are  different  substances.  There  are  several  words  and  different  spell- 
ings of  the  same  word  used  to  designate  the  substance — hydroquinol.  They  are : 
hydroquinon  (spelled  also  hydroquinone)  ;  hydrochinol  (spelled  also  hydrokinol)  ; 
hydrochinon   (spelled  also  hydrochinone,  hydrokinon,  and  hydrokinone). 


y6  ELEMENTARY  RADIOGRAPHY 

Pyro   Developing   Formula 
Pyrogallic  Acid  Solution 

"^  Avoirdupois  Metric  System 

Pyrogallic  Acid    i  ounce     30  grammes 

Sulphuric  Acid    20  minims i  c.c. 

Water  28  ounces    840  c.c. 

Soda  Solution 

Avoirdupois  Metric  System 

*Carbonate  of  Soda  (Anhydrous) 2  ounces 60  grammes 

*Sulphite  of  Soda   (Anhydrous) 3  ounces 90  grammes 

Water   28  ounces 840  c.c. 

To  Develop,  take 
"A,"  I  ounce  (30  c.c.)  ;    "B,"  i  ounce  (30  c.c.)  ;    Water,  8  ounces   (240  c.c).     This 
developer  will  then  contain  1.56  grains  Pyro  per  ounce. 

The  developer  may  be  made  and  kept  in  stock  solutions  as  above,  if 
desired.  A  better  plan  is  to  buy  the  prepared  developing  powders.  They 
may  be  purchased  at  any  photographic  supply  store.  The  chemicals  comic 
in  glass  tubes  or  packages  mixed  in  the  proper  proportions,  and  all  that 
is  necessary  to  make  the  solution  is  to  dissolve  them  in  the  quantity  of 
water  (distilled  or  tap  water  either)  suggested  on  the  package.  The 
package  or  tube  usually  contains  a  sufficient  quantity  to  make  4  to  8 
ounces  of  developing  solution.  The  advantages  of  this  over  mixing  the 
chemicals  yourself  are :  First,  the  convenience  and  saving  of  time,  and 
second,  only  small  quantities  being  made  at  one  time,  the  developer  is 
used  immediately,  and  is  therefore  always  fresh  when  used. 

A  developing  bath  does  not  keep  well  in  stock  solution  unless  the 
bottles  are  full  and  well  corked.  Even  then  discoloration  and  disintegra- 
tion occur  in  the  course  of  a  month  or  so.  It  is  always  advisable  to  use 
as  fresh  a  solution  as  possible.  Packed  in  the  box  with  the  plates  will 
always  be  found  a  formula  for  a  developer  recommended  by  the  manu- 
facturer of  the  plates.  It  is  not  at  all  necessary  to  use  the  particular 
developer  recommended. 

During  the  hot  summer  months  it  is  necessary 

temperature.  to  use  ice  in  the  developer,  ice  water  to  make  the 

solution,  or  place  the  tray  containing  the  developer 
in  another  larger  tray  with  ice  water  in  it.  If  the  developer  is  too  warm 
it  will  soften  the  emulsion,  cause  frilling  at  the  edges,  blistering  and 
fogging  of  the  negative.  The  developer  should  be  between  65  and  70 
degrees  F.  If  too  cold,  development  takes  place  slowly,  and  the  negative, 
when  finished,  is  pale  and  thin.  I  use  tap  water  in  the  winter  and  have 
no  trouble  due  to  improper  temperature.  In  the  summer,  though,  even 
using  ice  water  and  ice,  the  work  is  often  discouraging.  If  possible  dur- 
ing the  hottest  weather  defer  development  until  the  cool  of  the  evening. 

*If  crystals  are  used,  double  the  quantity. 


MAKING  RADIOGRAPHS 


77 


When    development    is    complete,    remove    the 
Tixillfl.  plate,  dip  it  in  clear  water,  then  immerse  it  in  the 

fixing  bath.  The  fixing  bath  is  a  solution  of  chem- 
icals which  dissolves  out  the  unaffected  silver.  Leave  the  plate  in  the 
fixer  for  two  or  three  minutes  after  the  milky  appearance  of  the  glass 
side  of  the  plate  has  disappeared.  A  plate  must  be  removed  promptly 
from  the  developer  as  soon  as  development  is  complete,  or  the  negative 
will  be  overdeveloped,  spoiled,  but  it  may  be  left  in  the  fixing  bath  for 
hours  longer  than  necessary  without  danger  of  spoiling  the  negative. 


Fig.  73.     Titubator. 


It  will  not  injure  the  plate  to  remove  and  replace  it  in  the  baths  at 
any  time  during  developing  or  fixing. 

The  actual  time  required  for  fixing  varies  from  5  to  20  or  30  min- 
utes. The  thicker  the  emulsion  the  longer  time  it  requires  for  fixing. 
Movement  of  the  fixing  solution  over  the  surface  of  the  plate  will  hasten 


78  ELEMENTARY  RADIOGRAPHY 

fixing.  A  titubator  (Fig.  y^))  is  a  machine  on  which  the  fixing  bath  tray 
may  be  set,  and  the  bath  kept  in  constant  movement  over  the  plate. 

When  several  negatives  are  being  made  at  the  same  time,  it  is  well 
to  use  a  fixing  box  (Fig.  74)  instead  of  a  tray.  If  the  plates  were  piled 
one  on  another  in  the  tray,  they  would  probably  stick  to  one  another  and, 
when  pulled  apart,  the  emulsion  would  be  scarred.  The  plates  stand  on 
end  in  the  fixing  box,  fitting  into  grooves. 

Hyposulphite  of  soda  is  the  standard  fixer.  There  are  not  a  great 
number  of  fixers,  as  there  are  of  developers,  to  choose  from.  Hypo- 
sulphite of  soda  and  water  alone  will  fix  plates,  but  is  not  so  efficacious 
as  when  other  chemicals  are  added  to  harden  the  emulsion. 

Acid-Fixing  Bath 

Avoirdupois  Metric  System 

Water  64      ounces  2  liters 

Hyposulphite  of  Soda 16      ounces  450  grammes 

Sulphite  of  Soda    (Anhydrous) ^  ounce  20  grammes 

When  fully  dissolved,  add  the  following  hardener : 

Powdered  Alum   1/2  ounce  15  grammes 

Citric  Acid 3^  ounce  15  grammes 

A\ stock  solution  may  be  made  as  given  in  the  foregoing  formula,  or 
the  prepared  fixing  powder  purchased,  and  the  fixing  bath  made  by  sim- 
ply dissolving  the  powder  in  a  stated  quantity  of  water.  There  is  nothing 
secret  about  the  formulas  of  the  prepared  fixing  powders.  They  are  all 
practically  the  same  as  the  formula  given.  The  advantage  in  using  them 
lies  in  the  saving  of  time  and  energy  that  would  otherwise  be  spent 
weighing  chemicals.  If  prepared  developing  and  fixing  powders  are  used, 
it  will  not  be  necessary  to  have  a  pair  of  scales  for  this  work.  A  grad- 
uated glass  for  measuring  liquids  will  be  all  that  is  needed.  During  the 
hot  months,  it  is  expedient — not  necessary — to  use  a  freshly  mixed  fixer. 
If  this  is  done  the  negative  is  less  likely  to  frill  or  blister.  Urllike  the 
developing  bath,  however,  the  fixing  bath  will  keep  without  disintegra- 
tion for  months.  If  scum  or  sediment  appears  after  standing  for  some 
time,  this  may  be  removed  by  filtering  the  solution  through  filter  paper 
or  cotton. 

The  temperature  of  the  fixer  should  be  at  least  as  low  as  that  of  the 
developer,  and  better  lower,  say  about  50  degrees  F. 

When  fixed,  if  the  plate. is  held  up  to  the  light  (any  light,  for  the 
plate  is  no  longer  sensitive  to  light),  the  shadow  of  the  bones  of  the  hand 
will  appear  as  transparencies;  the  flesh  shows  a  little  less  transparent 
than  the  bone,  and  the  balance  of  the  plate  will  be  opaque  and  black. 
Thus  the  shadows  show  light,  and  where  no  shadow  was  thrown  the  plate 
is  dark.  Hence  the  name  negative  which  is  applied  to  this  picture  on 
the  plate.     The  making  of  the  positive  picture  on  paper,  the  print,  as  it 


MAKING  RADIOGRAPHS 


79 


is  usually  called,  from  the  negative  will  be  described  presently.  The 
plate  is  no  longer  sensitive  to  white  light,  and  may  therefore  be  exposed 
to  it  any  time  after  having  been  in  the  fixer  a  minute  or  so. 

Great  care  must  be  exercised  not  to  get  any  of  the  fixing  bath  into 
the  developer.  A  very  little  "hypo"  will  spoil  the  developer.  It  is  well 
to  label  the  trays  so  that  the  tray  used  to  hold  the  fixer  one  time  will  not 
be  used  for  the  developer  another.  Or,  instead  of  labeling  the  trays,  a 
black  one  may  be  used  for  the  developer  and  a  white  tray  for  the  fixer. 


Fig.    74.     Fixing    box. 


Fig.    75.     Plate,    or   negative,    rack. 


When  fixing  is  completed  the  negative  must  be 
lUil$bing.  washed  in  clear  water  to  remove  all  "hypo"  from  it. 

If  the  negative  be  placed  in  a  tray,  the  tray  in  a 
basin  or  sink  and  the  tap  turned  on,  or,  in  other  wordc,  if  the  negative 
be  washed  in  running  water  it  requires  15  to  30  minutes  to  thoroughly 
wash  it.  Where  running  water  cannot  be  had,*  and  sometimes  during 
hot  weather  when  tap  water  is  too  warm,  the  negative  may  be  placed  in 
a  larger  vessel  of  water  and  left  for  about  an  hour,  changing  water  sev- 
eral times.  A  tray  of  water  used  on  a  titubator  is  efficient.  The  water 
must  be  changed  often,  and  the  time  required  is  about  three-quarters  of 
an  hour  or  longer.  When  several  negatives  are  being  made,  it  is  ad- 
visable to  use  a  washing  box  similar  to  the  fixing  box.     (Fig.  74.) 


*  "Runnii^g  water"  is  much  to  be  preferred,  as  the  friction  or  movement  of 
the  water  is  a  great  factor  in  cleansing  the  plate.  After  a  few  months  if  plates 
show  cloudiness,  or  a  metallic  luster  is  observed,  this  means  that  the  plates  were 
not  thoroughly  washed.  It  is  even  advisable,  after  washing,  to  rub  the  surface  of 
the  film  side  with  clean,  wet  cotton,  holding  the  plate  under  a  faucet  during  the  act. 


8o  ELEMENTARY  RADIOGRAPHY 

The  nexty  and  the  last  step  in  the  making  of  the 
Drying.  negative,  is  to  dry  it.     The  plate  should  be  set  on 

edge.  Drying  should  take  place  in  a  clean  atmos- 
phere, so  that  no  dust  or  soot  will  fall  on  and  stick  to  the  coated  surface 
of  the  negative.  Plate  racks  (Fig.  75)  may  be  used,  but  are  not  a  neces- 
sity. The  plate  may  be  set  on  edge  at  an  angle  of  about  95  degrees  by 
simply  leaning  it  up  against  some  perpendicular  wall.     (Fig.  76.)     Dry- 


Fig.    76.     Negatives    leaning   against    perpendicular   wall,    drying. 

ing  requires  several  hours.  It  may  be  hastened  by  placing  the  negative 
in  a  breeze.  By  immersing  the  negative  in  a  mixture  of  formalin  and 
alcohol,  then  placing  it  in  the  breeze  of  an  electric  fan,  drying  will  be 
very  materially  hastened.  The  use  of  the  formalin  and  alcohol  some- 
times causes  spotting  and  blurring  of  the  negative.  If  all  the  salts  of 
the  fixer  are  not  well  washed  out  of  the  emulsion,  it  will  not  dry  prompt- 
ly, but  will  become  rough  and  sticky,  and,  when  finally  dry,  it  will  be  full 
of  little  holes. 

Summarizing  the  making  of  the  negative,  it  consists  of  exposing, 
developing  (washing — mere  dipping  in  water),  fixing,  washing,  and  dry- 
ing. 

If  the  negative  when  finished  is  very  dark,  so  dark  that  parts  of  the 
image  are  lost,  the  plate  was  either  overexposed,  or  overdeveloped,  or 


MAKING  RADIOGRAPHS  8i 

both.  I  prefer  usually  to  say  that  it  was  overdeveloped,  for  even  if  it  had 
been  exposed  unnecessarily  long,  this  mistake  might  have  been  corrected 
by  leaving  it  in  the  developer  a  shorter  length  of  time.  If  the  negative 
is  almost  entirely  transparent  and  the  image  can  hardly  be  seen,  it  is  due 
to  underexposure,  or  underdevelopment,  or  both. 

The   mistake   of   overexposure   or   overdevelop- 
KcdUCCrs.  ment  can  be  corrected  to  an  extent  by  the  use  of  a 

"reducer." 
The  following  solution  is  a  reducer : 

*A.  Water    16  ounces    (480  c.c.) 

Hyposulphite  of   Soda 1  ounce       (30  grammes) 

B.  Water 16  ounces    (480  c.c. ) 

Potassium  Ferricyanide  1  ounce       (30  grammes) 

Mix  8  parts  of  solution  "A"  and  one  part  of  solution  "B,"  and  use  in  subdued 

light. 

The  i:!egative  can  be  placed  in  this  solution  directly  after  fixing, 
without  washing.  Or  it  may  be  washed — it  makes  little  or  no  difference. 
If  a  dry  negative  is  to  be  reduced,  it  must  be  soaked  in  water  for  at  least 
half  an  hour  before  placing  it  in  the  reducer.  When  sufficiently  reduced, 
wash  thoroughly  for  about  three-quarters  of  an  hour,  then  dry.  The 
work  of  reducing  may  be  done  in  any  light. 

When  not  in  use  keep  solution  "B"  protected  from  the  action  of 
light.  Remember  that  this  solution  is  one  of  the  most  powerful  poisons 
known.     Handle  it  with  extreme  caution. 

The  mistake  of  underexposure  cannot  be  cor- 

TntcnsifiCI*.  rected  to  an  appreciable  extent  by  any  means. 

The    mistake   of   an    underdevelopment    can   be 
corrected  to  an  extent  by  the  use  of  an  "intensifier." 

After  having  fixed  the  negative,  wash  it  well  in  running  water  for 

about  thirty  minutes  or  longer,  then  place  in  the  following  solution  : 

Mercuric    Bichloride    200      grains      (13.3  grammes) 

Potassium  Bromide    120       grains        (8.0  grammes) 

Water    65^  ounces     (195  c.c.) 

Keep  the  plate  in  this  solution  a  short  time,  when  it  will  be  observed 

to  be  bleached  uniformly  white  (the  longer  the  negative  is  bleached  the 

denser  it  will  ultimately  become).     Remove  from  the  bleaching  solution, 

wash  in  running  water  for  a  few  minutes,  then  blacken  in  the  following 

solution : 

Sodium    Sulphite    1  ounce       (30  grammes) 

Water  4  ounces   (120  grammes) 

Or 

Ammonia    20  minims     (1  c.c.) 

Water 1  ounce 

*  "Electro-Therapeutics  and  Roentgen  Rays,"  Kassaban. 


^2 


ELEMENTARY  RADIOGRAPHY 


When  sufficiently  blackened,  the  negative  is  again  washed,  then  dried. 
Intensifying  should  be  done  in  a  subdued  light — not  in  bright  daylight. 

An  old  negative,  one  which  has  been  made  for  some  time,  may  be 
intensified  by  first  soaking  in  water,  then  following  the  technic  given. 

Prepared  reducers  and  intensifiers,  with  directions  for  their  use,  may 
be  purchased  at  any  photographic  supply  house. 


Fig.    77.     Showing  how   the   printing  frame  is   held   up   to   the   light  to   expose   the   photographic 
paper.     Also  showing  the  back  of  the  printing  frame,  the   frame   half   open,  and  the  photographic 

paper    in    position. 


While  reducers  and  intensifiers  have  their  place  in  dental  radiog- 
raphy, they  are  used  only  to  correct  mistakes,  and  they  do  not  entirely 
correct  the  mistakes.  It  is  usually  expedient  to  make  a  new  negative 
rather  than  to  attempt  to  reduce  or  intensify  a  faulty  one. 

Round  transparent  spots  on  the  negative  are  caused  by  air  bubbles, 
or  air  "bells,"  as  they  are  called,  attaching  themselves  to  the  emulsion 
side  of  the  plate  while  in  the  developer. 

Spots  of  irregular  size  and  character  appearing  on  a  negative  are 
due  often  to  the  use  of  an  old  developer.  In  radiographic  work,  where 
the  appearance  of  a  spot  may  determine  a  diagnosis,  it  is  to  be  hoped  that 
fresh  developer  will  always  be  used.  By  fresh  developer  I  mean  de- 
veloper not,  at  most,  over  a  month  or  so  old,  having  been  kept  while  in 
stock  in  a  filled,  tightly  stoppered  bottle,  and  free  from  all  scum  and 
sediment.  A  developer  containing  pyrogallic  acid  disintegrates  so  rap- 
idly that  it  must  be  used  immediately  after  mixing — it  will  not  keep  at 
all.    "Pyro"  developers  stain  the  hands  badly. 


MAKING  RADIOGRAPHS  83 

When  the  negative  is  dry  we  are  ready  to  make 
Position  the   positive   pictures.      The   pictures   are    made   on 

Prlnt$,  sensitized  paper,  a  very  fine  grade  of  white  paper, 

one  side  of  which  is  coated  with  a  silver  salt  some- 
what as  plates  and  films  are  coated.  These  papers  sell  under  such  vari- 
ous names  as  Velox,  Cyko,  Artura,  and  Azo,  and  may  be  purchased  in 
any  size,  put  up  in  light-proof  packages.  Papers  are  not  as  sensitive  as 
plates  and  films,  and  an  orange  instead  of  a  ruby  light  may  be  used  in 
the  dark  room. 

Place  the  negative,  emulsion  side  up,  in  the  printing  frame  (Fig.  yy). 
Place  a  sheet  of  paper,  sensitive  side  down,  over  the  negative,  and  close 
printing  frame.  The  sensitive  side  of  the  paper  may  be  determined  by 
observing  that  the  paper  curls  slightly  toward  it ;  or  by  biting  a  corner 
of  the  paper,  when  the  sensitive  side  will  stick  slightly  to  the  teeth. 

To  make  the  exposure  now,  either  artificial  or  daylight  may  be  util- 
ized. Before  making  the  exposure  be  sure  that  the  balance  of  the  paper 
in  the  package  is  well  protected  against  the  light.  Hold  the  printing  frame 
so  the  light  will  shine  through  the  negative  and  strike  the  paper.  (Fig. 
yy.)  It  is  not  necessary  to  hold  the  printing  frame  immovable  during 
exposure.  The  time  of  exposure  varies  greatly  according  to  the  density 
of  the  negative ;  the  denser  the  negative  the  longer  the  exposure  must  be. 
Some  idea  of  the  time  of  exposure  necessary  may  be  learned  from  the 
directions  enclosed  with  the  paper.  To  make  the  print  for  Fig.  yi,  a 
16  c.p.  electric  light  was  used  holding  the  printing  frame  about  8  inches 
from  the  light  and  exposing  the  paper — Azo — 3  minutes. 

With  the  16  c.p.  light  turned  off,  in  the  orange 

Development  light,  the  paper  is  now  removed  from  the  frame.    As 

Of  Prints.  with  the  plate  there  is  not  the  slightest  change  in  the 

appearance  of  the  paper  after  exposure,  but  the 
image  is  there,  it  is  latent,  it  needs  only  to  be  developed. 

The  developing  formulae  for  papers  are,  broadly  speaking,  the  same 
as  for  plates.  It  is  very  important  that  the  developer  for  paper  be  freshly 
mixed,  for  the  slightest  discoloration  of  the  bath  will  soil  the  paper.  It 
is  not  desirable  to  save  the  developer  used  to  make  the  negative  and  use 
it  again  for  the  paper.  It  is  too  liable  to  cause  discoloration  of  the  print. 
"Pyro"  is  a  very  poor  developer  for  paper. 

Immerse  the  paper  quickly,  sensitive  side  up,  gently  passing  the  tips 
of  the  fingers  over  the  surface,  to  hasten  development  by  agitating  the 
developer,  and  to  keep  the  paper  submerged.  As  soon  as  the  image  ap- 
pears as  desired,  transfer  it  to  clean  water,  then  quickly  into  the  fixer. 
(It  is  kept  in  the  water  but  a  moment  or  so.)  If,  when  placed  in  the 
developer,  the  image  comes  up  so  quickly  that  it  gets  too  dark  before  it 


84  ELEMENTARY  RADIOGRAPHY 

can  be  transferred  to  water  and  fixer,  it  has  probably  been  overexposed. 
Shorten  the  time  of  exposure,  and  if  the  image  still  comes  up  too  quickly, 
dilute  the  developer.  If  the  image  appears  very  slowly  and  the  whites 
of  the  print  are  gray,  increase  the  time  of  exposure ;  if  the  whites  still 
come  gray,  add  a  few  drops  of  a  lo  per  cent,  solution  of  bromide  of  potas- 
sium to  the  developer.  >^ 

The  fixing  bath  for  prints  is  the  same  as  for  plates,  but  the  oath 
used  to  make  the  negative  should  not  be  saved  and  used  again  for  prints. 
It  might  discolor  them. 

Allow  prints  to  remain  in  the  fixer  15  to  20  minutes.  This  dissolves 
out  the  unaffected  silver. 

Next  wash  print  in  running  water  for  about  thirty  minutes.  No  visible 
change  occurs  in  the  print  from  the  time  it  leaves  the  developer.  Fixing 
and  washing  are  done  to  make  it  permanent.  The  temperature  of  the  de- 
veloper, fixer,  and  water  should  be  the  same  as  for  plates,  to  obtain  the 
best  results. 

When  thoroughly  washed  remove  the  prints  from  the  wash  water 
and  place  on  a  piece  of  clean  glass  face  down  one  on  the  other,  and 
press  out  the  water.  Then  lay  them  out  separately  on  a  frame,  covered 
with  cheese  cloth.  The  cheese  cloth  being  very  thin,  allows  the  prints 
to  dry  on  the  side  next  the  cloth  as  well  as  the  upper  side. 

When  dry  the  prints  may  be  mounted  on  cardboard. 


Dental  Radiography  or  Radioaontio.* 

CHAPTER   V. 

makiiid  Dental  Kaaiograpbs. 

In  the  foregoing  chapter  we  dealt  with  the  general  elementary  prin- 
ciples of  radiography.  We  shall  now  take  up  a  more  concrete  considera- 
tion of  dental  radiography. 

The  first  radiograph  of  the  teeth  was  exhibited  by  Prof.  Koenig  to 
the  Society  of  Physics  at  Frankfort-on-Main,  Germany,  in  February, 
1896 — only  a  few  months  after  the  discovery  of  the  X-ray.  Five  months 
later  an  article  appeared  in  Dental  Cosmos  by  Morton,  entitled  "  X-rays 
in  Dentistry."  Since  then  there  have  been  many  articles  written  on  the 
subject  and  published  in  various  dental,  medical,  and  Roentgenographic 
journals. 

For  convenience  in  describing  the  technic  involved  in  the  practice  of 
dental  radiography  the  subject  will  be  considered  under  the  following 
heads  :  ( i )  Manipulation  of  the  X-ray  machine  and  lighting  of  the  X-ray 
tube.  (2)  Posing  the  patient  and  adjusting  the  X-ray  tube  and  film  or 
plate.     (3)  Exposure.     (4)  Making  the  negative. 

Cbe  manipulation  of  tbe  X-Ray  niacbinc  and  Cidbting  of  tbe 
X-Ray  CuDc. 

Since  the  X-ray  machine  of  each  manufacturer  has  characteristics  of 
control  peculiar  to  itself  I  can  give  here  only  the  general  principle  of 
manipulation. 

As  the  reader  already  knows,  there  are  three  types  of  X-ray  machines 
in  general  use:     (i)  The  induction  coil.     (2)  The  high-frequency  coil. 


*  Radiodontia  is  a  new  word  coined  by  the  writer.  Radiodontia  is  the  science 
and  art  of  making  and  interpreting  radiographs  of  the  teeth  and  contiguous  parts. 

A  radiodontist  is  one  engaged  in  the  practice  of  radiodontia. 

These  words  will  be  found  quite  useful  and  have  been  promptly  adopted  by 
all  interested  in  the  subject  except  advocates  of  Roentgen  words,  who  believe  all 
X-ray  words  should  contain  the  proper  name  Roentgen,  no  difference  how  un- 
wieldy or  senseless  they  may  be. 

85 


86 


DENTAL  RADIOGRAPHY 


(3)  The  transformer.    We  shall  consider  the  manipulation  of  the  induc- 
tion coil  first. 

Different  induction  coils  have  a  different  number 

«Jl?T«'J.!!l5!lSVLi       of  controls  of  various  sorts.     Selecting  a  coil  with 

all  the  different  controls  I  shall  name  them,     (bee 


MAIN  SPARK  TERMINAL 


MILL  I  AMMETER 

VACCUM   REDUCINQ  LEVER 
SERIES  SPARK  QAP 


AMMETER 

VARIABLE  INDUCTANCE 
SWITCH 

RHEOSTAT  LEVER 
RESISTANCE  ALL   IN 


RESISTANCE  ALL  OUT-xf: 


SWITCH  LEVERS  TO 
PLATINUM  POINTS 


Fig.  78.     Induction  coil,  showing  the  various  controls. 

Fig.  78.)  First,  the  "on  and  off  switch";  second,  the  "pole  changer"; 
third,  "  the  rheostat  lever " ;  fourth,  interrupter  switches,  levers  and 
screws  "  to  platinum  points  " ;  fifth,  the  parallel  or  "  main  spark  "  gap ; 


MAKING  DENTAL  RADIOGRAPHS  87 

sixth,  the  "  vacuum  reducing  lever  " ;  seventh,  the  "  series  spark  gap  "  or 
inverse  current  spark  gap ;  eighth,  the  "  variable  inductance  switch." 

The  "  on  and  off  switch  "  is  the  one  by  means  of  which  the  current  is 
turned  into  the  machine.    This  control  is  on  all  coils. 

The  "pole  changer"  (Fig.  78)  is  a  double-throw  knife  switch  by 
means  of  which  the  secondary  current,  or  output  current  produced  by  the 
coil,  can  be  made  to  flow  in  either  direction — when  this  switch  is  down 
on  one  side  the  current  flows  in  one  direction,  when  it  is  down,  or  closed, 
on  the  other  side  it  flows  in  the  opposite  direction.  If,  after  the  tube  is 
connected  to  the  coil,  it  is  found,  by  the  manner  in  which  the  tube  lights, 
that  the  current  is  traveling  through  it  in  the  wrong  direction  (Fig.  48  and 
bottom  of  page  52)  the  tube  need  not  be  detached  and  re-attached  to  the 
coil ;  instead,  change  the  pole  changer  switch.  This  pole  changer  control 
is  found  on  comparatively  few  induction  coils. 

The  rheostat  controls  the  quantity  of  electricity  entering  the  machine 
and  so  the  quantity  produced  by  the  machine  to  be  sent  through  the  tube. 
(Fig.  30.)  On  very  large  induction  coils  it  is  often  inexpedient  to  cut  out 
all  of  the  resistance  of  the  rheostat,  while  on  the  smaller  ones,  and  the 
special  dental  X-ray  coils  of  the  induction  coil  type,  it  is  usually  necessary. 
Always,  when  the  current  is  turned  into  the  tube  for  the  first  time,  the 
rheostat  lever  should  be  on  a  low  button.  The  rheostat  control  is  found 
on  all  induction  coils. 

Multiple  point  electrolytic  interrupters  are  equipped  with  switches  by 
means  of  the  manipulation  of  which  only  one,  only  a  part,  or  all  of  the 
platinum  points  may  be  used.  Screws  or  levers,  or  both,  control  the  length 
of  the  platinum  exposed  in  the  electrolyte.  For  the  beginner  at  least  it 
is  best  that  the  interrupter  adjustment  be  made  or  set  and  its  further 
manipulation  avoided  as  much  as  possible.  If  more  than  three  points  are 
used  in  the  interrupter,  set  the  platinum  exposed  to  the  electrolyte  at  from 
y%  to  2/8  inches.  If  one  to  three  points  only  are  used,  set  the  exposure 
of  the  platinum  to  the  electrolyte  between  2/8  and  3/8  inches. 

Interrupters  are  made  which  adjust  themselves  automatically.  The 
end  of  the  platinum  rests  against  a  piece  of  porcelain.  It  is  weighted 
down  to  place,  and  thus  the  amount  of  platinum  exposed  remains  the  same 
always.  In  this  style  of  interrupter  base  metal  is  sometimes  used  instead 
of  platinum.  The  exposed  metal  disintegrates  and  wears  away  but  the 
weight  keeps  the  end  of  the  point  resting  against  the  porcelain  and  so 
the  amount  of  the  point  exposed  remains  the  same.     (Fig.  79.) 

The  parallel  spark  gap  may  be  manipulated  to  determine  the  number 
of  inches  of  spark  the  tube  will  back  up  and  so  determine  the  degree  of 
vacuum.     (Pages  42  and  43.)     As  the  operator  becomes  familiar  with  his 


88  DENTAL  RADIOGRAPHY 

tubes  and  machine  he  will  manipulate  this  gap  less.  It  is  the  practice  of 
some  men  to  set  this  gap  at  about  7  inches  and  leave  it  there,  resorting  to 
the  regulation  of  the  vacuum  of  the  tube  only  when  sparking  occurs  at  the 
parallel  spark  gap.  The  parallel  spark  gap  control  is  found  on  all  induc- 
tion coils. 

The  '"'  vacuum  reducing  lever  "  is  the  lever  by  means  of  which  the 
tube-regulating  spark  gap  (Pages  46  and  47)  is  made  wide  or  narrow. 
If  the  tube  will  light  properly,  and  no  sparking  occurs  at  a  6  to  8-inch 
parallel  spark  gap,  the  tube  requires  no  vacuum  regulation.  If  sparking 
occurs  across  6  to  8  inches  of  parallel  spark,  reduce  the  distance  of  the 


xfe^^r:^ 


Fig.    TU.      Self-adjusting   electrolytic   interrupter. 


tube-regulating  spark  gap  to  an  inch  or  two  and,  with  the  rheostat  on  a 
low  button,  turn  on  the  current  for  2  or  3  seconds.  This  may  be  repeated 
if  necessary  and  will  lower  the  vacuum  of  the  tube.  As  tubes  get  old, 
the  vacuum  gets  high,  and  they  become  "cranky."  To  handle  an  old 
tube  it  is  often  necessary  to  open  the  parallel  spark  gap  as  wide  as  pos- 
sible, and  set  the  tube-regulating  spark — 5  inches  for  a  slightly  "  cranky  " 
tube,  as  short  as  2  inches  for  a  very  high  "  cranky  "  tube — allowing  the 


MAKING  DENTAL  RADIOGRAPHS  89 

tube- regulating  spark  gap  to  remain  set  all  the  time  the  current  is  turned 
on.  The  object  of  the  operator  should  be  to  avoid  regulation  of  the 
vacuum  of  the  tube  as  much  as  possible. 

The  "  vacuum  reducing  lever  "  control  is  not  found  on  all  induction 
coils.  When  the  machine  does  not  afford  this  control,  the  width  of  the 
tube-regulating  spark  gap  is  controlled  by  means  of  a  movable  arm  at 
the  tube.     (Fig.  44.) 

The  "  series  spark  gap  "  or  inverse  spark  gap,  should  be  used  only 
when  necessary  to  cut  inverse  current  out  of  the  tube,  otherwise  the  gap 
should  be  closed.  If  a  valve  tube  (Figs.  51  and  52)  is  used  it  is  seldom 
necessary  to  make  a  series  spark  gap. 

By  means  of  the  "  variable  inductance  switch  "  the  output  current  of 
the  induction  coil  can  be  raised  or  lowered  in  voltage.  The  voltage  re- 
quired for  a  new  tube  is  not  as  great  as  the  voltage  required  for  an  old 
tube  with  a  higher  vacuum.  When  a  great  deal  of  inverse  current  is  seen 
in  a  tube  it  may  mean  that  the  induction  coil  is  generating  a  current  too 
high  in  voltage.  When  a  new,  unknown  tube  is  used  for  the  first  time  on 
an  induction  coil  with  an  inductance  switch,  start  with  the  lowest  voltage, 
and  the  rheostat  on  a  low  button.  Flash  the  current  through  the  tube, 
advance  the  rheostat,  flash  again  and  so  on  until  all  of  the  resistance  of 
the  rheostat  is  cut  out.  If  no  inverse  current  has  been  observed  in  the 
tube,  advance  the  inductance  switch  to  a  higher  voltage,  start  with  the 
rheostat  on  a  low  button  again,  flash  the  current  as  before  and  so  on,  ad- 
vancing to  a  higher  voltage  in  this  way,  until  the  tube  shows  inverse  cur- 
rent passing  through  it.  The  tube  should  be  operated  just  this  side  of  the 
point  where  inverse  current  appeared  in  it — say  for  example  on  inductance 
button  3,  rheostat  button  15.  If  the  tube  is  labelled,  inductance  3,  rheostat  1 5, 
it  may  be  used  with  the  machine  set  according  to  the  label  for  some  time. 
Comparatively  few  induction  coils  have  the  "  variable  inductance  "  control. 

Summary  of  Cccbnfc  The  technic  for  lighting  an  X-ray  tube  with  an 

tube  Wltb  TndUCtlon     induction  coil    (without  a  variable  inductance  con- 
Coil.  trol)  may  be  summarized  as  follows:     (i)  Test  the 

coil  by  means  of  the  on  and  off  switch,  starting  with  the  rheostat  on  a  low 
button  and  advancing  the  rheostat  between  test  flashes.  You  should  be 
able  to  obtain  at  least  5  or  6  inches  of  fat,  fuzzy,  parallel  spark.  This  step 
is  unnecessary  save  for  the  beginner  using  a  new  coil  for  the  first  few 
times.  It  shows  such  a  beginner  how  much  of  the  resistance  of  the  rheo- 
stat must  be  cut  out  to  obtain  a  fat,  fuzzy  spark.  It  shows  that  the 
machine  Is  operating  properly,  that  the  interrupter  is  properly  set.  On 
some  machines  with  terminals  of  the  right  shape  it  enables  the  operator 
to  determine  the  polarity  of  the  parallel  spark  gap  terminals.     (Page  42, 


90 


DENTAL  RADIOGRAPHY 


Fig.  40.)  (2)  Connect  the  tube  to  the  coil.  (3)  Set  the  parallel  spark 
gap  at  about  6  or  8  inches.*  (4)  With  the  rheostat  on  a  low  button  flash 
the  current  on.  Advance  the  rheostat  between  flashes.  If  the  current  is 
passing  through  the  tube  in  the  wrong  direction  change  the  pole  changer 
switch  or  reverse  the  attachment  of  the  tube  to  the  coil.  Once  the  polarity 
of  the  terminals  has  been  determined  the  operator  may  depend  on  this 
polarity  remaining  the  same,  unless  the  pole  changer  switch  is  changed, 
and  he  may  always  connect  the  tube  to  the  coil  accordingly.  //  sparking 
occurs  at  the  parallel  spark  gap,  lower  the  vacuum  of  the  tube.  //  in- 
verse current  is  seen  in  the  tube,  make  a  series  spark  gap  or  place  the 
rheostat  lever  on  a  lower  button,  A  little  inverse  current  in  a  tube  will 
not  materially  interfere  with  the  making  of  a  good  radiograph,  especially 
if  a  diaphragm  and  cone  or  cylinder  are  used.     (Fig.  65.)     The  great  dif- 


Fig.   SO.      Drawing   of  a  high-frequency   X-ray   machine   showing     various  controls. 


ficulty  in  the  technic  of  operating  an  induction  coil  is  the  problem  of  not 
allowing  inverse  current  to  pass  through  the  tube. 

The  controls  shown  in  Fig.  80,  for  a  high-fre- 

l)i9b-f Kqucncy  eon.  ^^^^^y  ^^^^  ^^^-  ^^'"^t'  ^^^^  frequency  control, 
labelled  "  high-frequency  "  and  "  X-ray  " ;  second, 
the  on  and  oH  switch,  labelled  "  switch  " ;  third,  the  "  rheostat " ;  fourth, 
the  "  regulating  spark  gap  " ;  fifth,  the  "  terminal  spark  gap  "  or  parallel 
spark  gap. 

By  means  of  the  "high-frequency"  and  "X-ray"  control  switch 
either  all  or  part  of  the  condenser  of  the  machine  is  used.  When  on  the 
"  X-ray  "  button  all  of  the  condenser  is  used  and  the  frequency  is  lower. 
This  button  is  sometimes  labelled  "  low  frequency  "  instead  of  "  X-ray." 


*  See  page  349  for  Soft  Tvibe  Technic. 


MAKING  DENTAL  RADIOGRAPHS  91 

This  control  is  found  only  on  machines  built  for  electro-therapeutic  work 
as  well  as  X-ray  worK. 

The  on  and  off  "  switch  "  turns  the  electricity  into  the  machine. 

The  "  rheostat "  controls  the  quantity  of  electricity  entering  machine. 

The  "  regulating  spark  gap  "  controls,  within  limits,  the  nature  of 
the  output  current  delivered  by  the  machine.  Widening  the  gap  increases 
voltage  at  the  expense  of  milliamperage,  narrowing  it  increases  milli- 
amperage  at  the  expense  of  the  voltage.  The  gap  should  be  as  narrow  as 
possible  with  the  voltage  high  enough  to  jump  the  maximum  parallel  spark 
gap.  (As  the  machines  of  this  type  are  now  built,  the  maximum  spark 
gap  is  usually  about  6  inches.)  This  gives  the  greatest  milliamperage 
obtainable  with  sufficient  voltage,  or  pressure,  to  force  the  current  through 
a  medium  or  medium-high  vacuum,  X-ray  tube.  The  metal  studs  at  the 
"  regulating  spark  gap  "  should  be  cleaned  occasionally :  Place  a  piece 
of  emery  cloth  or  sandpaper  between  the  studs,  screw  them  together  until 
they  hold  the  cloth  or  paper  loosely,  and  draw  the  cloth  or  paper  back  and 
forth  over  the  surface  of  the  stud. 

On  machines  of  this  type,  the  parallel  spark  gap  is  practically  always 
kept  at  its  maximum  width  for  X-ray  work.  If  sparking  occurs  across  it 
the  vacuum  of  the  tube  must  be  lowered.  When  the  tube  is  old  and  the 
vacuum  of  the  tube  cannot  be  lowered  sufficiently  to  stop  sparking  be- 
tween the  terminals  (remember  the  terminals  are  only  about  6  inches 
apart  on  this  type  of  machine)  the  writer  has  resorted  to  placing  a  piece 
'\f  glass  between  them.    This  is  a  strain  on  the  insulation  of  the  coil. 

Suminary  pf  tcchnic  The  technic  for  lighting  an  X-ray  tube  with  a 

f  or  Cigbting  X-Kay      iir  1  1  ,       rn 

Cube  wUb  Rigb=        high-trequency  coil  may  be  summarized  as  follows : 

Trcaueitcy  Coil.  (i)  open  the  parallel  spark  gap  to  its  maximum 
width,  i.e.  6  or  7  inches.  (2)  Cut  out  all  resistance  of  the  rheostat. 
(3)  Turn  on  the  on  and  off  switch  and  adjust  regulating  spark  gap  to  get 
as  fuzzy  a  spark  as  possible.  (This  should  be  done  as  quickly  as  possible 
so  the  current,  with  all  of  the  resistance  of  the  rheostat  cut  out,  will  not 
be  turned  into  the  coil  needlessly  long.)  (4)  Turn  current  off  and  con- 
nect tube  to  coil.  (Since  the  current  produced  by  this  machine  is  alternat- 
ing either  terminal  may  be  attached  to  the  anode  end  of  the  tube.) 
(5)  With  the  rheostat  on  a  low  button,  flash  the  current  through  the  tube. 
Advance  rheostat,  flash  again,  advance  rheostat  and  so  on  until  all  the 
resistance  of  the  rheostat  is  cut  out.  (6)  If  sparking  occurs  at  the  parallel 
spark  gap,  reduce  the  vacuum.  The  most  convenient  way  to  do  this  on  a 
machine  not  equipped  with  a  vacuum  reducing  lever,  where  the  vacuum 
is  controlled  by  a  movable  arm  at  the  tube  (Fig.  44),  is  to  set  the  arm  to 
give  a  certain  width  to  tube-regulating  spark  gap  and  leave  it  there.    For 


92 


DENTAL  RADIOGRAPHY 


new  tubes  the  tube-regulating  spark  gap  should  be  5  or  6  inches,  for  old 
tubes  2  or  3  inches,  this  to  be  governed  by  sparking  at  the  parallel  spark 
gap.  If  sparking  occurs  at  the  parallel  spark  gap  the  width  of  the  tube- 
regulating  spark  gap  should  be  reduced  until  this  ceases. 

In  case  the  high-frequency  coil  is  operating  on  a  direct  current  circuit 


MILUJ  flMMETEl^ 


TUBE       TERMINBI.S 


RUNNINq 
POSITION 


END    View 


Fig.  81.     Drawing  of  a  transformer  or  interrupterless  X-ray  machine    showing  various  controls. 

the  first  step  in  the  technic  of  manipulating  the  coil  is  to  set  the  rotary 
converter  in  motion.  This  is  accomplished  by  means  of  a  switch  and 
rheostat.    (Fig.  37.) 

_    .  „  _  The  controls  on  a  transformer  built  for  an  A.C 

manipulation  of  JJ.  C.     .      .,  i^-    ^  /it-     o  n    ^t,    »  ^u» 

translormm.  circuit  are:     First   (Fig.  81),  the      mam  switch    ; 

second,  the  synchronous  motor  switch,  a  two-pole, 

double  throw,  knife  switch  labelled  "  starting  switch  "  in  Fig.  81 ;  third, 


MAKING  DENTAL  RADIOGRAPHS  93 

the  "  on  and  off  switch  "  which  controls  the  output  current  of  the  ma- 
chine; fourth,  the  "pole  changer  switch";  fifth,  the  "rheostat"  which 
controls  the  quantity  of  output  current;  sixth,  the  "vacuum  reducing" 
lever. 

The  "  main  switch  "  simply  brings  the  current  up  to  the  machine. 

By  means  of  the  "  starting  switch  "  the  motor  is  set  in  motion.  This 
revolves  the  "  rectifier  switch."  The  switch  is  thrown  one  way  to  start 
the  motor,  then,  quickly  while  the  motor  is  in  motion,  to  the  other  side. 

When  the  "  on  and  off  switch  "  is  closed,  the  current  is  sent  into  the 
primary  of  the  transformer  and  immediately  the  secondary  current,  or 
output  current  of  the  coil,  jumps  the  parallel  spark  gap,  or,  if  an  X-ray 
tube  is  connected,  passes  through  it,  providing,  of  course,  the  vacuum  of 
the  tube  is  not  too  high. 

The  "pole  changer"  double  throw  switch,  works  on  exactly  the  same 
principle  as  the  pole  changing  switch  on  an  induction  coil.  Unless  the 
A.C.  transformer  is  equipped  with  an  indicator  one  never  knows,  before 
testing  the  current  through  the  tube,  which  is  the  positive  and  which  the 
negative  terminal.  Which  way  the  current  will  flow  depends  on  how  the 
rectifying  switch  happens  to  pick  it  up.  Some  machines  do  not  use  the 
"  on  and  off  switch  "  shown  in  Fig.  81,  but  eliminate  it  entirely,  and  use 
the  double-throw  pole  changer  switch,  trying  it  first  on  one  side,  then  on 
the  other,  if  necessary,  to  send  the  current  through  the  tube  in  the  right 
direction. 

The  "  rheostat  "  controls  the  amount  of  current  entering  the  primary 
winding  of  the  transformer  and  so  controls  the  strength  of  the  output 
current. 

The  lever,  or  sliding  rod,  for  reducing  the  vacuum  on  a  transformer 
is  practically  the  same  as  the  lever,  or  sliding  rod,  for  the  same  purpose 
on  an  induction  coil.     (Figs.  78  and  45.) 

Summary  of  CechniC  The  technic  for  lighting  an  X-ray  tube  with  an 

Cub{  With  H  C.         ^■^'   transformer  may  be  summarized  as   follows  : 
transformer.  (i)  Connect  the  X-ray  tube  to  the  coil.    Either  ter- 

minal may  be  attached  to  the  anode.  (2)  Have  the  parallel  spark  gap 
about  6  or  7  inches  wide.*  (3)  With  the  rheostat  on  button  i  flash  the 
current  through  the  tube.  (4)  If  the  current  is  not  passing  through  the 
tube  in  the  right  direction  reverse  the  pole  changer  switch.  (5)  Advance 
the  rheostat,  with  intermittent  flashes,  until  the  desired  amount  of  current 
passes  through  the  tube.  According  to  the  machine  used  and  to  the  length 
of  time  the  operator  wishes  to  give  for  exposure,  the  current  sent  through 
the  tube  may  be  anywhere  from  10  to  20  milliamperes  to  as  much  as  40 
or  50  milliamperes.     (Practically  all  machines  of  this  type  are  equipped 


*  See  page  349  for  Soft  Tube  Technic. 


94  DENTAL  RADIOGRAPHY 

with  milliammeters.)  If  the  machine  used  is  a  very  smaU  one  (one  of 
the  special  dental  machines)  all  of  the  resistance  of  the  rheostat  is  usually 
cut  out,  if  the  machine  is  a  large  one,  from  a  half  to  three-fourths  of  the 
resistance  of  the  rheostat  is  cut  out. 

If,  when  the  current  is  first  flashed  through  the  tube,  some  sparking 
occurs  at  the  parallel  spark  gap,  lower  the  vacuum  of  the  tube  by  reducing 
the  tube  regulating  spark  gap  to  an  inch  or  so  and,  i^ifh  the  rheostat  on  a 
very  loiv  button,  turn  the  current  on  for  about  2  or  3  seconds.  If  the 
rheostat  is  advanced  too  far  when  the  vacuum  of  the  tube  is  lowered,  too 
much  current  will  pass  through  the  regulating  chamber  and  the  vacuum 
of  the  tube  will  be  made  too  low.  Transformer  tubes  require  rery  little 
vacuum  regulation  and  the  less  done  the  longer  the  tube  will  give  good 
service. 

When  lighting  a  tube  with  a  transformer  no  manipulation  is  neces- 
sary to  eliminate  inverse  current  from  the  tube,  for  the  machine  produces 
no  inverse  current.  This  simplifies  the  manipulation  for  tube  lighting 
tremendously. 

Summary  of  CccbniC  The  technic  for  lighting  an  X-ray  tube  with  a 

^^CubC^wUb  DC         ^-C  transformer  is  so  much  like  the  operation  of  an 
transformer.  A.C.  transformer  that  a  summary  of  it  would  be  sim- 

ply a  repetition  of  technic  already  given.  There  are,  however,  two  points 
of  diiTerence  to  which  I  direct  your  attention. 

The  first  step  in  operating  a  D.C.  transformer  is  to  start  a  rotary  con- 
verter and  this  is  done  by  means  of  a  switch  and  rheostat. 

Because  the  current  from  the  rotary  converter,  and  not  the  line  cur- 
rent, enters  the  primary  of  the  transformer  in  a  D.C.  transformer,  polarity 
of  the  terminals  always  remains  the  same,  unless  the  pole  changing  switch 
is  changed.  Thus  it  is  not  necessary  to  test  the  current  through  the  tube 
or  observe  an  indicator  each  time  to  learn  which  way  the  current  is  flowing 
when  using  a  D.C.  transformer  as  it  is  when  using  an  A.C.  transformer. 
Once  the  operator  learns  which  terminal  is  positive  he  may  depend  on  it 
this  terminal  will  remain  positive  always,  unless  the  pole  changing  switch 
is  changed  and  he  mav  connect  his  tube  to  the  coil  accordinsrlv. 


Posing  m  Patient  and  JIdjusting  the  X=Rav  CuDe  and  Tilm  or  Plate. 

Dental  radiographs,  or  odontoradiographs,  have  been  divided  into  two 
classes:  (i)  The  intra-oral  and  (2)  the  extra-oral.  Intra-oral  radio- 
graphs are  made  by  holding  films  in  the  mouth ;  extra-oral  radiographs 
are  made  on  plates,  or  films,  usually  plates,  placed  outside  of  the  mouth 
for  exposure. 


MAKING  DENTAL  RADIOGRAPHS 


95 


Tntra-Oral 
Kadiosrapbs 


It  makes  no  difference  what  sort  of  a  radiograph 
is  to  be  made,  it  should  always  be  borne  in  mind, 
while  posing  the  patient  and  adjusting  the  tube  and 
plate,  or  film^  that  you  are  using  your  X-rays  as  a  source  of  light  to  cast  a 
shadow  of  some  object — i.e.,  the  object  being  radiographed — on  a  screen — 
i.e.,  the  film  or  plate. 

To  impress  this  idea  more  firmly  in  your  mind  observe  Fig.  82.    The 
source  of  light,  the  candle,  casts  a  distorted — an  elongated — shadow  of 


Fig.  82. 


the  object,  a  plaster  of  Paris  tooth,  on  a  white  screen.  As  you  observe  this 
illustration  contemplate  what  would  have  to  be  done  to  overcome  the  ex- 
treme distortion  of  the  shadow  and  make  it  approximately  the  same  length 
as  the  tooth.  Is  it  not  true  that  either  the  light  must  be  moved  upward  or 
the  screen  must  be  placed  more  nearly  parallel  with  the  tooth,  or  perhaps 
a  little  of  both?  If  you  follow  this  reasoning  you  are  on  the  way  to  mak- 
ing proper  poses  for  radiographs,  for  the  principle  involved  is  the  same. 
The  ideal  pose  for  making  a  radiograph  is  to  have  the  focal  ray,  or 
central  ray,  indicated  by  the  pointer  at  the  end  of  the  cylinder  in  Fig.  83, 
directed  to  strike  the  object  being  radiographed,  and  the  plate  or  film, 


96 


DENTAL  RADIOGRAPHY 


at  right  angles.     (See  Fig.  70.)     This  is  impossible  much  of  the  time  in 

the  practice  of  radiodontia. 

Distance  Between  ^^  ^^^  beginner  first  attempts  posing  patient  and 

X-Ray  Cube  and        adjusting  his  tube  his  first  question  is,  "  How  close 

Patient.  should  I  place  the  tube  to  the  patient?  "    If  the  tube 

stand  used  is  one  with  a  cone  or  cylinder,  the  length  of  the  cone  or  cylinder 

will  govern  this.     The  cone  or  cylinder  will  almost  touch  the  patient. 

If  a  shield  like  the  one  shown  in  Fig.  64  is  used  let  the  distance  between 

the  glass  of  the  tube  and  the  patient's  face  be  an}^vhere  from  6  to  about 

12  inches. 


Fig.  83. 

Proper  posing  can  be  taught  best  by  observation  of  illustrations,  but 
before  proceeding  further  with  the  subject  of  posing  we  should  stop  and 
consider  the  films  used  for  dental  X-ray  work. 


Dental  X-Kay 
Tilms. 


The  Eastman  Kodak  Co.  supplies  films  espe- 
cially prepared  for  intra-oral  dental  X-ray  work,  in 
three  sizes:  No.  i  film  1%  by  i^  inches,  No.  lA 
film  i^  by  2%.  inches  and  No.  2  film  2^  by  3  inches.  These  films  are 
supplied  in  packets,  two  films  to  a  packet,  wrapped  in  black  paper  to  pro- 
tect them  from  ordinary  light,  over  which  is  wrapped  oil  paper  to  protect 
them  against  moisture  when  placed  in  the  mouth.  The  most  populai  size 
is  the  No.  i.* 


*A  new  size  film,   1^  by  2  inches,  suggested  by  the  writer  for  the  posterior 
teeth,  has  just  been  placed  on  the  market. 


MAKING  DENTAL  RADIOGRAPHS  97 

There  are  two  kinds  of  Eastman  X-ray  films  :  "  Positive  "  films  and 
"  negative  "  films.  The  names  "  positive  "  and  "  negative  "  are  mislead- 
ing. They  give  one  the  idea  that  there  is  some  difference  in  the  films 
without  suggesting  at  all  what  the  difference  is.  The  differences  between 
the  "  positive  "  and  "  negative  "  Eastman  X-ray  films  are  :  The  "  posi- 
tive "  is  less  sensitive  than  the  "  negative  "  film ;  it  therefore  requires  a 
longer  exposure  than  the  "  negative  "  film  and  need  not  be  handled  with 
the  same  care  in  the  dark  room.  Radiographs  made  on  the  "  positive  " 
film  are  more  "  contrasty  "  than  those  made  on  the  "  negative  "  film. 

It  is  a  matter  of  interest  to  know  how  the  names  "  positive  "  and 
"  negative  "  happen  to  be  applied  to  the  Eastman  films.  The  first  films 
supplied  to  the  dental  profession  for  X-ray  purposes  by  the  Eastman  Co, 
were  cinematograph — i.e.,  motion  picture  films — cut  to  the  proper  size  and 
covered  with  black  paper.  There  are  two  kinds  of  cinematograph  films, 
the  negative  and  the  positive.  The  negative  is  the  one  used  in  the  motion 
picture  cameras  to  obtain  the  original  negatives  of  the  scenes  and  action 


Fig.  84.  A,  rubber  dain  stretched  out  and  fastened  to  a  board  with  pins.  B,  the  rubber  covered 
with  cement  and  the  iilm  packet  on  it.  C,  pins  removed  from  one  end  and  the  rubber  lapped 
over  packet.     D,  all  pins  removed.      E,  excess  rubber  trimmed  oft'. 

pictured.  The  positive  film  is  the  one  used  to  make  the  "  reels  "  used  in 
the  projection  lanterns  at  the  motion  picture  theaters.  The  "  reels  "  made 
on  the  positive  film,  for  the  projection  lanterns  are  made  from  the  original 
negative  made  on  the  negative  film.  It  is  not  unlikely  that  the  words 
pocitive  and  negative  will  soon  be  displaced  by  the  words  slow  and  fast : 
The  positive  films  will  La  known  as  the  slow  films,  the  negative  as  the 
fast  films. 

Besides  the  films  prepared  especially  for  dental  X-ray  purposes,  the 
Eastman  Co.  also  makes  films  of  all  standard  sizes — i.e.,  4  by  5  inches, 
5  by  7  inches,  6^-^  by  8^  inches — put  up  in  light-proof  packages  of  i  or  2 
doz.  films. 

If  he  desires  to  do  so  the  operator  may,  in  his  dark  room,  cut  these 
larger  films  to  any  desired  size  or  shape  and  cover  them  with  black  paper 
himself.  For  protection  againct  moisture  he  may  cover  the  black  paper 
with  rubber  dam — Fig.  84.  Or  he  may  take  a  piece  of  mending  tissue, 
such  as  is  used  by  tailors  to  mend  clothing,  of  such  size  that  when  folded 
over  the  film  packet  (Fig.  84C  and  D)  it  will  extend  beyond  the  packet 


98  DENTAL  RADIOGRAPHY 

on  the  three  open  sides,  about  one-half  inch.  Warm  the  edges  of  the 
tissue  slightly  by  passing  it  over  the  flame  of  an  alcohol  lamp,  or  Bunsen 
burner,  and  pinch  them  together.  Then  warm  them  (the  edges)  to  stick- 
iness again  and  turn  them  back  and  stick  them  to  the  tissue  covering  the 
back — i.e.,  the  non-sensitive  side — of  the  film  packet. 

There  is  no  particular  advantage  derived  from  preparing  one's  own 
film  packet,  and  the  practice  is  rapidly  being  discontinued.  When  the 
X-ray  machine  used  is  small  and  the  time  of  exposure  is  long,  it  may  be 
found  expedient  sometimes  to  give  more  protection  against  moisture  than 
is  afiforded  by  the  oil  paper  of  the  prepared  film  packet. 

For  the  time  being,  owing  to  the  war  in  Europe,  the  Eastman  is  the 
only  available  X-ray  film  so  far  as  I  am  able  to  learn.  The  Ilford  and  the 
S.chleussner  are  X-ray  films  manufactured  abroad. 


Fig.  85.     Position  of  film  in  mouth  for  making  radiographs  of  the  upper  cuspid,  bicuspid  and  first 

molar    region. 

The  smooth  side  of  the  Eastman  film  packet,  the  opposite  side  to  the 
one  on  which  the  ends  of  the  covering  paper  lap,  represents  the  sensitive 
side  of  the  enclosed  films.  When  placing  the  film  packet  in  the  mouth 
have  the  sensitive  side  of  the  films — i.e.,  the  smooth  side  of  the  packet — 
present  toward  the  teeth.  Except  when  intensifying  screens  are  used  (see 
index:  intensifying  screen)  the  sensitive  side  of  films  and  plates  always 
present  toward  the  object  to  be  radiographed  and  the  X-ray  tube. 

With  the  film  placed  In  the  mouth  as  per  Fig.  85 

Posterior  tectb.        *^  P°^^  should  be  as  in  Fig.  86.    Figure  87  is  a  dia- 
grammatic illustration  of  the  pose  shown  in  Fig.  86. 
With  the  film  placed  in  the  mouth  as  per  Fig.  85,  Fig.  88  represents 
an  incorrect  pose.     The  angle  at  which  the  X-rays  are  directed  at  the 


MAKING  DENTAL  RADIOGRAPHS 


Fig.  86.      The  correct  pose  for  making   ra.liouraplis   (if   th  •   upper  bicuspid  and  molar   region  and 
a  radiograph   made   from   the   pose. 


Fig.  87.  Diagrammatic  illustration  of  pose  seen  in  Fig.  86,  showing  the  X-rays  striking  the  tooth 
and  film  at  such  an  angle  as  to  avoid  either  lengthening  or  shortening  of  the  shadow  cast 
on   the   film.       (Schematic   drawirg   after    Dr.    Price) 


100 


DENTAL  RADIOGRAPHY 


Fig. 


Incorrect   pose   for   radiographing   the   upper   bicuspids   and   molars,    and    a   radiograph 
made  from  the  pose. 


Fig.  89.     Diagrammatic  illustration  of  the  pose  seen  in  Fig.  88,  showing  the  X-rays  striking  the 
tooth  and  film  at  such  an  angle   as  to  cause  elongation  of  the  shadow  cast  on  the  film. 


MAKING  DENTAL  RADIOGRAPHS 


lOI 


#^- 


Fie 


90.   Incorrect  pose  for  radiographing  upper  bicuspids  and  molars,   snd  a   radiograph   made 

from  the  pose. 


f/LM 


Fig.  91.      Diagrammatic  illustration  of  the  pose  seen  in  Fig.  90,  showing  the  X-rays  striking  the 
tooth   and  film  at  such  an  angle  as  to  cause  shortening  of  the  shadow  cast  on  the  film. 


I02 


DENTAL  RADIOGRAPHY 


teeth  and  film  is  not  right.  This  position  of  the  tube  would  be  correct,  if 
the  film  were  parallel  with  the  teeth ;  but  it  is  impossible  to  place  the  film 
in  this  relation  to  the  upper  teeth.  Fig.  89  is  a  diagrammatic  illustration 
of  the  pose  shown  in  Fig.  88. 

With  the  film  placed  in  the  mouth  as  per  Fig.  85,  Fig.  90  illustrates 
another  incorrect  pose.  The  X-rays  do  not  strike  the  teeth  and  film  at 
the  correct  angle  and  the  teeth  in  the  resulting  radiograph  are  too  short. 
Fig.  91  is  a  diagrammatic  illustration  of  the  pose  shown  in  Fig.  90. 

A  study  of  Figs.  87,  89  and  91  will  show  that  in  order  to  make  a 
radiograph  which  will  not  picture  the  teeth  too  long  nor  too  short  the 


♦•m» 


Film 


Fig.    92. 


X-rays  should  strike  the  film  almost,  but  not  quite,  at  right  angles  to  its 
surface.  This  same  idea  has  been  expressed  thus :  "  The  X-rays  should 
be  directed  at  right  angles  to  a  neutral  line  drawn  between  the  film  and 
the  tooth."  Another  writer  expresses  the  same  idea  so :  "  Bisect  the 
angle  made  by  the  plane  of  the  teeth,  and  the  plane  of  the  film,  and  direct 
the  rays  so  they  will  fall  perpendicularly  to  this  bisecting  plane." 

The  angle  of  the  film  in  Figs.  87,  89  and  91  is  what  it  would  be  in  the 
average  mouth.  Suppose,  however,  the  vault  is  very  flat.  In  such  an 
event  the  angle  of  the  X-rays  as  illustrated  in  Fig.  87  to  be  correct,  would 
cause  a  marked  lengthening  of  the  shadow,  as  illustrated  by  the  dotted 
lines  and  drawing  in  Fig.  92.  The  angle  of  the  X-rays  should°be  as  in 
Fig.  91  to  avoid,  as  nearly  as  possible,  any  distortion.  (Notice  in  Fig.  92 
that  the  bending  of  the  film  would  cause  a  lengtbening  of  the  shadow.) 


MAKING  DENTAL  RADIOGRAPHS 


103 


Just  in  proportion  as  the  vault  becomes  more  flat  the  film  departs 
from  the  vertical  and  the  tube  must  be  at  a  different  and  higher  angle. 
And  so,  inversely,  as  the  vault  is  higher  the  film  may  be  placed  more 
nearly  parallel  with  the  teeth  and  the  tube  may  be  lowered. 

From  the  foregoing  it  will  be  understood  why  we  can  never  be  sure 
that  our  radiograph  gives  the  exact  length  of  upper  teeth. 

By  making  slight  changes  in  the  positions  of  the  film  as  illustrated 


Fig.  9o.     Position  of  film  in  the  mouth  for  radiographing  upper  anterior  teeth.     See  pose  Fig.  94. 

in  Fig.  85  and  the  tube  as  illustrated  in  Fig.  86,  all  of  the  teeth  from  the 
third  molars  forward  to  the  cuspids  (and  in  some  mouths  the  laterals) 
can  be  radiographed. 

Figure  g-?  illustrates  the  position  of  the  film  for 
Pose  for  the  Uvdci*         ^  ■  ^■         ^        r    ^ 

TInterior  teeth  niakmg    radiographs    of    the    upper    anterior    teeth. 

While  bending  of  the  films  is  to  be  avoided  as  far 
as  possible,  because  it  causes  distortion  of  the  radiographic  image,  when 


I04 


DENTAL  RADIOGRAPHY 


Fig.  94.  Correct  pose  for  radiographing  upper  aiiteriur  tueth  with  film  in  the  mouth  as  in  Fig. 
93.  Radiograph  made  from  this  pose.  (It  tooli  the  writer  a  long  time  to  learn  that,  when 
radiographing  upper  anterior  teeth,  it  is  best  to  try  to  radiograph  only  two  teeth  at  a  time, 
to  bend  a  part  of  the  film  deliberately  in  order  to  avoid  bending  all  of  it  (Fig.  101)  and  to 
have  the  patient  hold  it  with  the  thumb,  not  the  fingers  or  finger.) 


MAKING  DENTAL  RADIOGRAPHS  105 

the  film  is  placed  in  this  position  it  is  sometimes  unavoidable,  especially 
in  a  mouth  with  a  V-shaped  dental  arch.  A  small  ball  of  cotton  under  the 
film,  in  the  palate,  will  sometimes  assist  in  preventing  too  much  bending, 
without  at  the  same  time  holding  the  film  too  far  away  from  the  teeth. 

With  the  film  placed  in  the  mouth  as  in  Fig.  93,  the  pose  for  making 
radiographs  of  the  upper  anterior  teeth  is  illustrated  in  Fig.  94. 

Another  position  for  the  film  when  making  radiographs  of  the  upper 
teeth  is  illustrated  in  Fig.  95.  The  sensitive  side  of  the  film  presents 
toward  the  teeth.  The  film  is  held  in  position  by  having  the  patient  close 
the  mouth.    Fig.  96  illustrates  the  pose  with  the  film  in  the  position  shown 


Fig.  95.     Position  of  the  film  in  the  mouth  for  pose  and  radiograph  seen  in  Fig.  96. 


in  Fig.  95.  A  radiograph  made  in  this  way  is  liable  to  considerable  dis- 
tortion. The  radiograph  in  Fig.  96  was  made  when  radiographers  pre- 
pared their  own  film  packets,  cutting  a  film  of  the  desired  size  from  a 
large  film  and  wrapping  it  in  black  paper.  I  quote  from  the  first  edition 
of  this  book :  "  After  making  a  radiograph  as  shown  in  Fig.  96,  it  may 
be  trimmed  to  a  more  symmetrical  form.  In  other  words,  the  film,  as 
wrapped  tip  in  a  film  packet  may  be  left  an  indefinite,  unsymmetrical 
form  and  trimmed  to  a  more  pleasing  outline  after  the  radiograph  is 
made.'* 

With  the  film  placed  in  the  mouth  as  shown  in 

^To$tIr[ort«tbT''     ■^'^-  ^^'  ^^^  correct  pose  for  making  radiographs  of 

the    lower   molar    region    is    illustrated    in    Fig.    98. 

Note  that  the  rays  are  directed  at  the  teeth  and  film  at  right  angles.     If 

the  radiograph  resulting  from  this  pose  does  not  show  the  apices  of  the 


io6 


DENTAL  RADIOGRAPHY 


Fig.  9G.     The  pose  with  the  film  in  the  mouth  as  in   Fig.   95  and  the  radiograph  made  from  this 

pose. 


teeth,  press  the  fihii  down  farther  if  possible.  If  this  cannot  be  done  the 
tube  must  be  tipped,  slanting  the  rays  upward,  something  like  the  rays  are 
slanted  downward  for  the  upper  teeth,  or  the  head  may  be  tipped  side- 
ways from  the  tube  which  accomplishes  the  same  thing. 

With  the  film  placed  in  the  mouth  as  shown  in  Fig.  99  the  pose  for 
making  radiographs  of  the  lower  cuspids  and  bicuspids  is  illustrated  in 
Fig.  100.  Note  that  the  rays  are  directed  disto-XingnaMy  and  slightly  up- 
ward. 


MAKING  DENTAL  RADIOGRAPHS  107 

Figure  loi  shows  the  film  packet  placed  in  posi- 
Poses  for  the  Eower  ^-^^  ^^^  radiographing  the  lower  anterior  teeth. 
Note  that  about  ten  millimeters  of  the  packet  is  bent 
abruptly  backward.  This  is  done  because  the  packet  is  too  wide  for  the 
dental  arch  and  it  is  better  to  bend  back  a  part  of  the  film  abruptly,  and 
so  allow  the  film  to  go  to  place,  than  to  bend  the  entire  film  in  an  effort 
to  get  it  into  a  space  too  narrow  for  it.  A  little  cotton  between  the  film 
and  inner  surface  of  the  dental  arch  sometimes  helps  in  preventing  undue 
bending  of  the  film. 

Figure  102  is  the  correct  pose  for  making  radiographs  of  the  lower 
anterior  teeth  with  the  film  in  the  mouth  as  per  Fig.  loi.    Owing  to  the 


Fig.  97.     Position  of  the  film  in  the  mouth  for  radiographing  the  lower  molars.     See  pose  Fig.  9S- 

difficulty  in  placing  the  film  parallel  with  the  teeth,  without  bending  the 
surface  of  the  film  too  much,  it  is  usually  necessary  to  tip  the  head  back- 
ward and  direct  the  rays  upward  and  lingually  in  order  to  make  the  apices 
of  the  roots  show  in  the  radiograph. 

With  the  film  placed  in  the  mouth  as  shown  in  Fig.  95,  except  that 
the  sensitive  side  presents  toward  the  lower  teeth,  a  radiograph  may  be 
made  from  the  pose  shown  in  Fig.  103.  Such  a  radiograph  is  liable  to 
great  distortion. 

A  study  of  Fig.  104  will  assist  the  operator  materially  in  directing  the 
rays  through  the  parts  at  the  proper  angle.  From  this  illustration  one 
can  promptly  see  why  the  shadow  of  the  mesiobuccal  root  of  upper  molars 
is  usually  thrown  to  the  mesial  of  the  lingual  root,  while  the  shadow  of 


io8 


DENTAL  RADIOGRAPHY 


Fig.  98.  Pose  for  radiographing  the  lower  molars  with  the  film  in  the  mouth  as  in  Fig.  97. 
Radiograph  made  from  this  poee.  The  film  holder  in  use  is  illustrated  in  Figs.  331,  332 
and  333. 


the  disto-buccal  is  superimposed  on  the  lingual  root.  (Fig.  105.)  The 
shadow  of  the  disto-buccal  root  can  sometimes  be  thrown  to  the  distal  of 
the  lingual  root  by  directing  the  X-rays  through  the  part  in  a  disto-\mg\.\?i\ 
direction. 

When  radiographing  lower  molars  it  is  often  necessary  to  direct  the 
rays  through  the  part  in  a  disto-\mg\id\  direction  to  obtain  a  clear  outline 


MAKING  DENTAL  RADIOGRAPHS 


109 


of  the  roots.  This  sometimes  superimposes  the  two  mesial  canals  one  over 
the  other.  Observe  the  roots  of  the  second  molar  on  the  reader's  left  in 
Fig.  104  and  note  that  directing  the  rays  straight  through— i^.,  at  right 
angles  to  the  long"  axis  of  the  tongue— would  cast  the  mesio-buccal  canal 
on  the  film  to  the  mesial  of  the  mesio-hngual  canal. 

There  are  various  methods  of  holding  the  film 
in  the  mouth  during  its  exposure  to  the  X-rays.  The 
different  poses,  already  illustrated,  show  the  methods 


metboas  of  1)0lding 
films  in  the  nioutb. 


Fig.    99. 


Position    of    film    in    the    mouth    for   radiographing   lower   cuspid    and   bicuspid    region. 
See  pose  Fig.  100. 


now  in  use  by  the  writer.  For  the  upper  teeth,  the  patient  holds  the  film, 
with  the  thumb  usually.  For  the  lower  posterior  teeth  the  film  holder 
illustrated  in  Fig.  333  is  used.  For  the  lower  anterior  teeth  the  patient 
holds  the  film  with  the  finger  or  with  the  Leach  film  holder.  The  set  of 
Leach  film  holders,  designed  by  Dr.  Floyd  Leach  of  Chicago,  illustrated 
in  Fig.  106,  have  been  in  the  hands  of  the  writer  only  a  few  days  now — 


no 


DENTAL  RADIOGRAPHY 


Fig.  100.  Pose  for  radiographing  the  lower  cuspid  and  bicuspid  region  with  the  position  of  the 
filin  as  in  Fig.  99.  Radiograph  made  from  this  pose.  Tipping  the  tube  is  not  necessary 
and  not  advisable  if  the  film  can  be  placed  down  far  enough. 


an  insufficient  length  of  time  to  give  them  a  fair  trial.  It  may,  neverthe- 
less, be  stated  that  the  Leach  film  holders  will  be  found  very  useful, 
especially  to  the  beginner. 

Dr.  Tousey,  of  New  York  City,  and  Dr.  Ketcham,  of  Denver,  have 
also  designed  special  dental  film  holders. 

I  am  not  inclined  to  consider  the  question  of  the  operator  or  assistant 
holding  the  film,  further  than  to  warn  you  against  the  practice.     (See 


MAKING  DENTAL  RADIOGRAPHS 


111 


chapter  VIII.)     Do  not  do  it;  the  repeated  exposure  is  dangerous.    Have 
the  patient  hold  the  film. 

Some  difficulty  due  tO'  gagging  is  sometimes  experienced  when  the 
film  is  held  in  position  for  upper  second  and  third  molars.  To  patients 
who  will  not  tolerate  the  film  in  this  location,  I  sometimes  say  this :  "  I 
know  you  cannot  keep  from  gagging  when  something  tickles  your  palate. 
But,  did  you  know  this?  you  can  keep  from  gagging  as  long  as  you  can 
hold  your  breath/'    Unless  the  X-ray  machine  used  is  a  small  one  the 


Fig.  101.  Position  of  film  for  radiographing  lower  anterior  teeth.  See  pose  Fig.  102.  The 
principle,  here  illustrated,  of  deliberately  bending  a  part  of  the  film  in  order  to  avoid  bend- 
ing all  of  it,  is,  perhaps,  the  most  important  and  fundamental  single  thing  to  be  learned 
about  the  application  of  films  to  the  mouth.  This  principle  is  applicable  not  only  to  the 
lower  anterior  region,  but  to  other  parts  of  the  mouth  as  well,  particularly  the  upper  ante- 
rior part._  To  make  the  radiograph  illustrated  in  Fig.  102  the  film  was  bent  abruptly  back- 
ward a  little  on  both  sides  instead  of  on  one  side   only  as  illustrated  here. 

exposure  can  be  made  while  the  patient  "  holds  the  breath."  (The 
psycho-therapist  may  analyze  this  treatment  for  gagging  to  his  heart's 
content.) 

Plates  are  usually  used  in  preference  to  films  for 
extra-oral  radiographs  because  they  are  easier  to 
handle  and  cheaper.  If  the  negative  is  to  be  sent 
through  the  mail  it  is  best  to  make  it  on  a  film.  If  films  are  used,  two 
films  may  be  exposed  simultaneously  and  so  two  negatives  made  from  one 
exposure.    This  is  always  an  advantage  in  that  if  one  film  is  not  developed 


extra-Oral 
Radiographs. 


112 


DENTAL  RADIOGRAPHY 


Fig.  102.  Pose  for  radiographing  tlie  lower  anterior  teeth  with  the  position  of  the  film  as  in 
Fig.  101.  Radiograph  made  from  this  pose.  (Note  the  rubber  matting  covering  the  patient 
where  one  of  the  terminals  of  the  tube  is  brought  close  to  the  body.  The  rubber  matting 
acts  as  an  insulation  preventing  sparking  of  the  current  into  the  patient.) 


MAKING  DENTAL  RADIOGRAPHS 


113 


Fig.  103.  Pose  for  radiographing  the  lower  anterior  teeth  with  the  film  flat  against  the  occlusal 
surfaces  and  incisal  edges.  Radiograph  made  from  this  pose.  (Note  rubber  matting  insula- 
tion again.) 


114 


DENTAL  RADIOGRAPHY 


properly  or  becomes  spotted  or  mutilated  in  some  way  the  mistake  or 
accident  may  be  corrected  when  the  other  film  is  developed.  Also,  if  the 
case  is  a  referred  one,  one  negative  may  be  kept  on  file,  and  the  other 


Fig.  104.  Horizontal  section  of  the  upper  and  lower  jaws  cut  a  little  beyond  the  free  margin 
of  the  alveolar  process,  showing  the  forms  and  positions  of  the  roots  of  the  various  teeth. 
(From  Cryer's  "Internal  Anatomy  of  the  Face.") 


sent  to  the  dentist  or  physician  who  referred  the  patient.  The  Eastman 
dental  films,  No.  3,  4  x  6  inches,  and  No.  4,  8  x  10  inches  are  prepared 
in  packets  containing  "  a  pair  "  of  films,  for  extra-oral  work. 

A  number  of  manufacturers  supply  special  X-ray  plates.     (See  chap- 


MAKING  DENTAL  RADIOGRAPHS  115 

ter  IV,  page  66.)  The  Brady  product  is  particularly  worthy  of  consid- 
eration because,  when  it  was  first  placed  on  the  market  it  was  the 
"  fastest  "  X-ray  plate  thus  far  made,  and  so  it  enabled  men  with  small 
X-ray  machines  to  do  extra-oral  dental  radiographic  work,  who  had 
hitherto  found  this  work  impossible,  owing  to  the  limited  power  of  their 
machines  and  the  insufficient  sensitivity  of  X-ray  plates  to  the  action  of 
the  X-rays. 

The  size  of  the  plate  used  for  extra-oral  work  may  be  4  x  5,  5  x  7, 
65^  X  8^  or  8  X  10  inches.  As  the  operator  learns  to  pose  his  patient  and 
adjust  his  plate  and  tube  with  accuracy  he  will  use  a  smaller  plate.  The 
beginner  had  perhaps  better  start  by  using  the  8  x  lo-inch  plate.  The 
size  of  the  plate  selected  will,  of  course,  depend  primarily  on  the  size  of 
the  field  the  operator  wishes  to  place  under  radiographic  observation. 


Fig.   105.      Radiograph  showing  three  roots  of  the  upper  first  molar;  the  mesio-buccal   root  is  to 
the  mesial,  the  disto-buccal  root  and  the  lingual  root  are  superimposed  one  upon  the  other. 

For  the  technic  of  handling  the  plate  preparatory  to  making  the  radio- 
graph see  Chapter  IV,  pages  68,  69  and  70. 

The  best  possible  advice  I  can  give  the  man  who 

Posterior  Cecth  contemplates  doing  any  amount  of  extra-oral  dental 

radiographic  work  is  that  he  obtain  a  skull  and  refer 

to  it  often  to  assist  him  in  posing  his  patient  and  adjusting  the  plate  and 

X-ray  tube.     He  should  also  make  many  experimental,  test  radiographs 

of  the  skull. 

Extra-oral  radiographs  are  made  by  having  the  patient  lay  the  head 
against  the  plate — which  rests  on  a  flat  surface — and  directing  the  rays 
through  the  parts  from  above.  (Figs.  107  and  108.)  The  side  next  to 
the  plate — i.e.,  the  side  farthest  from  the  X-ray  tube — is  the  one  being 
radiographed  in  such  a  position.  The  big  problem  in  posing  for  radio- 
graphs of  this  kind  is  to  so  arrange  the  plate,  the  patient's  head  and  the 
tube  as  to  prevent  superimposition  of  the  two  sides  of  the  mouth. 


ii6 


DENTAL  RADIOGRAPHY 


Superimposition  of  parts  may  be  avoided,  to  variable- extents,  in  three 
ways.  ( I )  By  tipping  the  tube  in  such  a  way  as  to  direct  the  rays  through 
the  parts  diagonally.  (Fig.  107.)  (2)  By  the  use  of  an  incline  plane — 
wooden  pillow  or  wedge — 23  degrees.  (Fig.  108.)  (3)  By  directing  the 
patient,  who  will  first  naturally  assume  the  position  shown  in  Fig.  107, 
to  "  turn  the  head  until  the  nose  touches,  or  almost  touches,  the  plate." 
(By  having  the  patient  turn  the  head  farther,  until  the  nose  is  flattened 
to  one  side  against  the  plate,  satisfactory  radiographs  of  the  lower  anterior 
teeth  may  be  made.) 


Fig.   lOG.     Leach  film  holders.     The  holder  in  the  middle  is  seen  in  use  in  Fig.   102. 


The  tube  should  not  be  tipped  as  in  Fig.  107  when  the  incline  plane 
is  used :  When  the  incline  plane  is  used  direct  the  rays  straight  down- 
ward. 

Figure  109  is  the  radiograph  made  from  the  pose  shown  in  Fig.  108. 

As  has  been  indicated  in  Figs.  107  and  108,  extra-oral  dental  radio- 
graphs may  be  made  with  the  patient  lying  on  a  table  or  seated  on  a  chair 
or  stool  with  the  head  placed  on  a  stand  or  table.  Figure  no  illustrates 
a  special  tube  stand  attachment  on  which  the  head  may  be  placed.    Figure 


MAKING  DENTAL  RADIOGRAPHS 


117 


no  also  illustrates  a  device  for  holding  the  head  immovable.  The  writer 
prefers  the  reclining  position,  however,  when  sufficient  office  space  will 
permit  the  use  of  a  table. 

While  satisfactory  radiographs  of  the  lower 
anterior  teeth  (see  above)  may  be  made  on  plates 
placed  extra-orally,  sufficiently  clear  radiographs  of 

the  upper  teeth  cannot  be  obtained  by  any  means  thus  far  devised,  on 

plates  so  placed. 


Pose  for  tbc 
^Interior  tcctb. 


Fig.   107. 


Po$«$  for  the  Cranial 
Sinuses  and  Cells. 


There  is  such  similarity  in  the  symptoms  caused 
by  dental  lesions  and  those  produced  by  diseases  of 
the  cranial  sinuses  and  cells  that  the  radiodontist  is 
not  infrequently  called  upon  to  make  a  differential  diagnosis.  The  cranial 
sinuses  and  cells  are  (i)  the  maxillary  sinuses,  or  antra,  (2)  the  frontal 
sinuses,  (3)  the  ethmoid  cells,  (4)  the  sphenoid  cells  and  (5)  the  mastoid 
cells. 

With  the  patient's  face  placed  against  the  sensitive  side  of  the  plate. 
Fig.  Ill  illustrates  a  standard  pose  for  making  radiographs  to  give  an 


ii8 


DENTAL  RADIOGRAPHY 


Fig.  108.  Pose  for  making  the  radiograph  seen  in  Fig.  109.  The  patient  is  Ivins  on  a  table 
^t^.°r',tl^nHi'l''H'T^l.^'?''i?  holds  apart  the  wires  attached  to  the  regulat  ng  Ihamber  and 
useful)  ■  ^^""^  ^""P^^      ^'^^^  spreader"  will  often  be  found  quite 


MAKING  DENTAL  RADIOGRAPHS  119 


Fig.   109.      Radiograph  made  from   pose  illustrated  in   Fig.   108. 


120 


DENTAL  RADIOGRAPHY 


anteroposterior  view  of  the  frontal  sinuses,  the  ethmoid  cells  and  the 
antra.  (A  better  pose  is  illustrated  and  diagramed  in  Appendix  Chap. 
V.)  Observe  Figs.  112  and  113  made  from  this  pose.  (Figure  iii 
shows  one  end  of  a  small  chain  attached  to  the  metal  of  the  tube-manipu- 
lating apparatus.  The  other  end  of  the  chain  is  attached  to  a  gas  jet  or 
water  pipe.  This  is  called  "  grounding  the  current  "  to  keep  it  from  jump- 
ing a  small  air  gap  into  the  patient.  The  tube  is,  of  course,  insulated 
from  the  metal  of  the  tube-manipulating  apparatus  and  cylinder,  but,  be- 
cause the  electric  current  in  use  is  of  such  high  potential  or  pressure, 


Fig.  110. 


Tube  stand  with  attachment   for  making  extra-oral   radiographs. 

Eisen.) 


(Photograph  by  Dr. 


some  current  may,  nevertheless,  get  into  the  metal  parts,  and  from  there 
to  the  patient.  With  a  small  chain,  or  any  electric  conductor,  attached 
to  the  metal  of  the  tube-manipulating  apparatus  and  the  other  end  at- 
tached to  a  gas  jet  or  water  pipe  the  current  will  not  jump  an  air  gap 
into  the  patient  but  will  pass  into  the  chain  and  through  it  to  the  gas  or 
water  pipe,  eventually  reaching  the  earth  possibly — hence  the  name 
grounding.  If  the  current  jumps  a  small  air  gap  into  a  patient  a  spark 
occurs,  due  to  the  atmospheric  resistance,  and  the  sensation  experienced 
by  the  patient  is  very  definitely  unpleasant.) 

Figure  114  is,  in  results  obtained,  the  same  as  the  pose  illustrated  in 


MAKING  DENTAL  RADIOGRAPHS 


121 


Fig.  III.     In  Fig.  114  an  incline  plane  is  used  and  the  rays  are  directed 
straight  downward. 

A  studied  observation  of  Fig.  112  will  reveal  to  the  reader  a  hori- 
zontal shadow  across  the  antra.  If  you  will  remove  the  skull  cap  from  a 
skull  and  look  at  the  floor  of  the  cranial  cavity  you  will  see  that  this 
shadow  represents  the  petrous  portion  of  the  temporal  bone.     The  tube  is 


Fig.   111.      Pose  for  making  radiographs  of  the  Antra  of   Highmore 


tipped  (Fig.  11 1)  or  an  incline  plane  is  used  (Fig.  114)  in  order  to  throw 
this  shadow  as  far  downward  toward  the  teeth  as  possible. 

_A  straight-through  lateral  view  of  the  antra  may  be  made  to  locate 
foreign  bodies  in  it.     (Figs.  277  and  278.) 

Intra-oral  radiography  of  the  antra  is  not  a  success.  (See  Fig.  275. 
Text  on  page  235  and  236.) 

Figure  276  was  made  from  a  pose  similar  to  Fig.  108.    One  antrum, 


122 


DENTAL  RADIOGRAPHY 


the  one  closer  to  the  plate,  is  outlined  with  the  dotted  lines,  the  other 
may  be  seen  as  the  light  area,  to  the  reader's  left  and  a  little  above  the 
outlined  antrum. 


Fig.  112.  Radiograph  made  from  the  pose  illustrated  in  Fig.  111.  A,  B,  frontal  sinuses. 
C,  D,  orbits.  E.  F,  ethmoid  cells.  F  does  not  show  as  well  as  E  because  the  cells  of  this 
side  are  full  of  pus.  G,  H,  Antra  of  Highmore,  I,  J,  nasal  cavity.  As  an  aid  in  reading 
the  radiograph  observe  Fig.  113. 


The  sphenoid  cells  are  situated  back  of,  and  a  little  below,  the 
ethmoid  cells.  Radiography  of  these  cells  is  very  difficult  and  in  the  hands 
of  most  operators  attended  with  little  success.    (See  Appendix,  Chap.  V.) 

For  a  consideration  of  the  radiographv  of  the  mastoids  see  Appendix, 
Chap.  V. 


MAKING  DENTAL  RADIOGRAPHS 


123 


Exposure 

When  the  patient  and  tube  are  properly  posed,  before'  placing  the 
film  or  plate  in  position,  flash  the  current  through  the  tube  once  or  twice 
so  that  the  patient  may  become  acquainted  with  the  light  and  noise  pro- 


Fig.  113.     Same  as  Fig.  112. 


A,  frontal   sinuses.  _    B,   orbits. 
E.  nasal  cavity. 


C.    ethmoid   cells.      D,    antra. 


duced.  Otherwise  the  patient  might  be  startled  when  the  current  is  first 
sent  through  the  tube,  move,  and  so  spoil  the  radiograph. 

All  films,  plates  and  photographic  paper  should  be  kept  in  a  lead. 
X-ray-proof  box,  except  just  at  the  time  of  exposure.     Fig.  115. 

When  making  radiographs  of  the  lower  teeth  with  the  film  in  the 


124 


DENTAL  RADIOGRAPHY 


mouth  the  patient  should  be  warned  not  to  swallow  during  the  exposure. 
Movement  of  the  tongue  in  swallowing  would  move  the  film. 

As  stated  in  Chapter  IV  (see  on  page  71 )  a  num- 
titnc  ot  €XP0$UK.      ber  of  things  influence  the  time  of  exposure  neces- 
sary.    For  example,  if  the  exposure  necessary  when 
using  the  slow  Eastman  film  is  4  seconds,  all  other  factors  may  remain 
the  same,  ^nd  the  exposure  necessary  for  a  fast  Eastman  film  will  be 
only  about  i  second. 


Fig.   114.   Pose  for  frontal  sinuses,  antra  and  ethmoid  cells  using  incline  plane. 


Distance  Between 

target  and  film  or 

Plate. 


The  distance  between  the  target  of  the  tube  and 
the  emulsion  of  the  plate,  or  film,  exerts  a  great  in- 
fluence on  the  time  of  exposure  necessary.  This 
distance  varies  from  about  10  to  20  inches.  The  time  of  exposure  neces- 
sary varies  directly  with  the  square  of  the  distance.  The  square  of  10  is 
100,  the  square  of  20  is  400.  Thus  the  exposure  at  20  inches  should  be 
four  times  as  long  as  at  10  inches.  It  has  been  suggested  that  the  distance 
between  the  target  and  the  film  be  standardized  at  about  20  inches.  This 
is  all  right  for  men  with  large  machines  but  the  men  who  use  the  smaller 
machines  will  find  it  expedient  to  have  the  distance  less. 

Age  increases  the  density  of  osseous  tissue  and  so  the  time  of  ex- 
posure necessary  to  make  dental  radiographs  varies  slightly  directly 
according  to  the  age  of  the  patient. 

The  time  of  exposure  for  the  molars,  intra-orally  is  a  little  longer 

than  for  the  other  teeth  because  the  rays  must  penetrate  the  malar  bone 

for  the  upper  molars,  and  the  oblique  ridges  for  the  lower  molars. 

€x»0$U1*C  Ulitl)  tbe  Since  the  type  and  size  of  X-ray  machine  used 

Different  types  of      governs  the  milliamperage  sent  through  the  X-ray 

X-Ray    lllacbines.       tube,   obviously  this  governs  to  a  great  extent  the 

time  of  exposure  necessary.     Taking  into  account  the  machines  of  all 


MAKING  DENTAL  RADIOGRAPHS  125 

sizes  which  are  in  general  use  the  time  of  exposure  necessary  with  IN- 
DUCTION COILS,  for  intra-oral  dental  radiographs,  varies  from  a  frac- 
tion of  a  second  to  about  15  or  20  seconds,  for  extra-oral  dental  radio- 
graphs, from  about  i  or  2  seconds  to  about  45  seconds ;  with  HIGH- 
FREQUENCY  COILS,  for  intra-oral  dental  radiographs,  from  about 
3  to  30  seconds,  for  extra-oral  dental  radiographs,  from  about  12  seconds 
to  about  I  minute ;  with  TRANSFORMERS,  for  intra-oral  dental  radio- 
graphs, from  a  fraction  of  a  second  to  about  5  seconds,  for  extra-oral 
dental  radiographs,  from  a  fraction  of  a  second  to  about  10  seconds. 

INDUCTION  COILS,  of  various  sizes  operating  at  their  full 
capacity,  are  capable  of  forcing  from  4  or  5  to  about  18  +  milliamperes 
through   a   tube  backing  up   5   or  6   inches   of   parallel   spark;   HIGH- 


Fig.  115.     Lead-lined,  X-ray-proof  box  for  photographic  supplies. 

FREQUENCY  COILS  from  about  3  to  about  8  milliamperes ;  TRANS- 
FORMERS from  about  12  to  about  60  -)-  milliamperes.  (The  plus  mark 
placed  after  milliamperage  18  for  induction  coils  and  60  for  transformers 
is  put  there  in  recognition  of  exceptional  X-ray  machines  of  these  types 
which  are  capable  of  delivering  a  higher  milliamperage.  As  I  say,  how- 
ever, these  largest  machines  are  exceptional,  i.e.,  not  the  type  of  machine 
commonly  met  with.)  Ordinary  X-ray  tubes,  gas  tubes,  as  they  are  called 
since  the  advent  of  the  new  Coolidge  tube,  could  not  take  a  current  of 
60  milliamperes  for  much  longer  than  about  i  second  continuously  with- 
out injury  to  the  tube  from  overheating. 

When  the  time  of  exposure  is  over  5  seconds  it  is  best  to  make  the 
exposure  intermittently :  turn  the  current  on  for  5  seconds  then  off  for  5 
seconds,  then  on  for  5  seconds  and  so  on  until  the  desired  time  of  exposure 


126 


DENTAL  RADIOGRAPHY 


is  given.  This  avoids  overheating  the  tube,  and  so  lowering  of  the  vacuum 
by  heating  the  regulating  chamber. 

When  the  time  of  exposure  is  i  or  2  seconds,  or  less,  an  automatic 
time-switch  may  be  used  to  advantage.     Fig.  ii6. 

X-ray  tubes  should  not  be  used  until  they  become  so  hot  the  hand  can 
not  be  placed  on  them.  Heating  takes  place  particularly  in  the  region  of 
the  cathode.  If  used  until  hot  a  tube  should  be  allowed  to  cool  before  it 
is  used  again.    If  much  radiographic  work  is  being  done  it  is  economy  to 


Fig.   116.      Automatic  time   switch  or  "  timer,"  ty  means   of  which   seconds  may  be   split. 


have  at  least  three  tubes.     (The  new  Coolidge  is  an  exception  to  this  rule 
as  it  is  to  almost  all  rules  regarding  X-ray  tubes.) 

With  the  milliamperage,  the  condition  of  the  tube,  and  the  emulsion 
on  the  plate  remaining  the  same,  it  requires  an  exposure  about  four  times 
as  long  for  an  extra-oral  dental  radiograph  as  for  an  intra-oral  one.  This 
increase  in  the  length  of  time  necessary  for  the  extra-oral  dental  radio- 
graph is  due  to  increased  distance  between  the  target  and  film,  increased 
thickness  of  tissue  to  be  penetrated  by  the  rays  and  increased  distance 
between  the  object  being  radiographed  and  the  plate. 


MAKING  DENTAL  RADIOGRAPHS  127 

The  exposure  necessary  for  frontal  sinus  and  antrum  radiographs 
with  the  pose  as  in  Figs.  11 1  and  114,  is  longer  than  for  radiographs  of 
any  other  part  of  the  body.  To  avoid  straining  tubes  for  radiographs  of 
this  kind  it  is  often  expedient,  and  with  small  machines  necessary,  to  use 
an  intensifying  screen. 

An  intensifying  screen  is  a  piece  of  paper  or 
Tntcnsifyiltg  SCfCCns  card  board  covered  with  some  such  material  as  cal- 
cium tungstate  or  platino-barium  cyanide.  By  its 
use  exposure  may  be  shortened  from  ^  to  4/5. 

The  coated  side  of  an  intensifying  screen  is  placed  against  the  coated 
side  of  the  film,  or  plate,  and  both  screen  and  film  are  placed  in  the  light- 
proof  packet  as  usual.  Thus  we  get  a  double  action  on  the  film  when 
it  is  exposed,  the  action  of  the  X-rays  themselves  and  the  action  due  to 
the  fluorescence  of  the  intensifying  screen. 

When  using  an  intensifying  screen  the  uncoated  side  of  the  film 
should  present  toward  the  object  being  radiographed.  This  is  contrary 
to  the  rule  that  to  obtain  the  best  results  the  coated  side  of  the  plate  or 
film  should  present  toward  the  object  to  be  radiographed. 

The  advantages  of  the  intensifying  screen  are:  (i)  Just  in  propor- 
tion as  it  reduces  the  time  of  exposure  it  protects  both  patient  and  op- 
erator against  any  ill-effects  of  the  X-rays.  (2)  By  shortening  the  time 
of  exposure  the  life  of  the  tube  is  lengthened.  (3)  By  using  an  intensi- 
fying screen  one  is  able  to  do  tolerably  rapid  work  even  with  a  small  coil. 

The  disadvantages  of  the  intensifying  screen  are:  (i)  It  causes  a 
granular  appearance  of  the  negative,  blotting  out  detail.  (2)  It  is  liable 
to  spot  the  negative,  due  to  unequal  fluorescence  of  its  surface.  (3)  It 
fluoresces  for  a  minute  or  so  after  exposure,  and  if  the  plate  and  screen 
do  not  maintain  their  exact  relation  to  one  another  blurring  of  the  nega- 
tive results.  (4)  For  intra-oral  dental  work  unless  one  owns  several 
screens,  so  that  a  number  of  film  packets  may  be  made  at  a  time,  their 
use  necessitates  the  making  of  a  film  packet  before  each  exposure,  which 
is  discommoding. 

Such  grosser  lesions  as  an  impacted  tooth,  for  example,  can  be 
radiographed  satisfactorily  with  the  intensifying  screen,  but  when  we 
wish  to  obtain  detail,  such  as  is  necessary  to  observe  pulp  stones  or  a 
necrotic  condition,  for  example,  the  use  of  the  intensifying  screen  is 
contraindicated.    An  intensifying  screen  disintegrates  with  use. 

Because,  as  I  have  said,  the  intensifying  screen  fluoresces  for  some 
time  after  the  exposure  has  been  made  it  has  been  the  practice  of  radiog- 
raphers to  lay  the  plate  and  screen  aside  for  some  time  before  disturbing 
their  relation  to  one  another.  Dr.  Sidney  Lange,  however,  believing  that 
the  continued  fluorescence  will  cause  blurring  of  the  negative  even 
though  the  relation  of  the  screen  to  the  plate  be  not  disturbed,  removes  the 
plate  from  the  screen  immediately  after  exposure.  His  results  from  this 
practice  are  excellent. 

Figure  117  is  a  dental  radiograph  made  with  an  intensifying  screen. 

Intensifying  screens  should  be  cleaned  often  by  brushing  the  sensitive 
side  with  a  very  soft  brush. 


128 


DENTAL  RADIOGRAPHY 


Unless  the  reader  desires  to  master  the  method 
Pertinent  JIdVice.  of  determining  the  time  of  exposure  by  the  milli- 
ampere-second  method  (see  Appendix  to  Chap.  V, 
Page  355)  the  most  practical  advice  I  can  give  is:  Learn  from  the 
manufacturer  of  the  coil  where  to  set  the  rheostat  and  the  time 
he  considers  right  for  dental  radiographs.  Make  an  exposure,  giv- 
ing the  time  of  exposure  advised.  Develop  the  film  in  Eastman 
M.  Q.  tube  developer,  6  fluid  ounces  of  water  to  the  tube  of  devel- 
oper, for  5  minutes ;  or  use  the  Brady  "  four-minute  "  developer  for  4 
minutes,  or  the  Brady  "6-minute"  developer  for  6  minutes.  Remove 
from  the  developer,  dip  in  water  and  fix  in  the  fixing  solution.  Now  then 
if  the  film  is  too  pale,  as  it  probably  will  be — for  most  manufacturers 
seem  to  think  their  coils  will  make  dental  radiographs  in  shorter  ex- 
posures than  is  really  necessary  or  best — increase  the  time  of  exposure,  or 
advance  the  rheostat,  or  shorten  the  distance  between  the  target  and  film 


Fig.   117.      Dental   radiograph  made   with  an  intensifying  screen. 

and  try  again.  If  the  negative  is  too  dark,  and  it  has  been  left  In  the 
Eastman  developer  only  5  minutes  or  the  Brady  developer  only  4  or  6 
minutes,  the  exposure  has  been  overtimed. 


ItlaKiitd  tl)c  negatii^c. 

The  subject  of  making  negatives  has  already  been  covered  fairly 
well  in  Chapter  IV. 

What  developer  shall  we  use?     I  obtained  the 

Choice  of  Developer,      formulas  for  the  developers  used  by  twelve  different 

radiographers,  and  they  were  all  different !     From 

this  we  may  conclude  that  any  clean,  properly  mixed  developer  will  do 

the  work. 

However,  I  would  advise  the  beginner  to  use  one  of  the  developers 
just  referred  to  in  the  foregoing,  i.  e.,  a  developer  which  will  have  the 
desired  action  in  a  known  length  of  time.     When  making  the  developing 


MAKING  DENTAL  RADIOGRAPHS 


129 


Fig.  118.     Dark  box  for  use  where  a  dark  room  is  not  available. 


solution,  dis.solve  the  light  powder  first,  then  the  heavier,  white  powder. 
As  the  operator  becomes  acquainted  with  the  technic  of  development  he 
can  correct  slight  mistakes  in  exposure  by  leaving  the  plate,  or  film,  in  the 
developer,  say,  for  example,  only  4  minutes  in  the  5-minute  developer 
for  overtimed  films,  or  7  minutes  for  undertimed  films.  It  is  unnecessary 
to  leave  any  plate  or  film  in  the  5-minute  developer  longer  than  10 
minutes.  If  the  image  does  not  appear  as  it  should  in  10  minutes  it 
never  will ;  a  longer  exposure  must  be  made. 

If  at  all  possible  it  is  desirable  to  have  a  dark  room,  but  if  such  a 
room  is  not  available,  a  dark  box  may  be  used.    Fig.  118. 

Figure  119  illustrates  a  satisfactory  method  of  hanging  film  negatives 
up  to  dry. 


130 


DENTAL  RADIOGRAPHY 


To  expedite  handling  it,  when  the  film  negative  is  dry  it  may  be 
mounted  between  2  pieces  of  clear  glass  using  passe-partout  strips  to  bind 
the  pieces  of  glass  together  or  it  may  be  placed  in  a  special  radiomount. 
Figure  120. 

If  several  radiographs  are  made  of  the  same  patient  it  is  best  to 
mount  them  all  between  two  pieces  of  glass  of  suitable  size,  (Fig.  121) 
or  in  a  mount  of  celluloid  and  card  board.     (Fig.  121A.) 


Film  119.      Films  hung  up  to  dry. 

Summary  Of  Steps  in  (0    Pose   the   patient.      (2)    Test   the   current 

tecbniC  for  niakiug      through  the  X-ray  tube.     (3)  Place  the  film  or  plate 
Radiographs-  in  position.    (4)  Make  the  exposure.    (5)  Make  the 

negative.     (6)  Prepare  the  negative  for  observation  and  study. 


In  appearance  and  size  the  Van  Woert  develop- 

"i2!!.5-?n''!?S'^*      ing  tank   for   dental   X-ray  films   is   not  unlike  the 
Developing  vanK.  *   ,    ,  ,  .  ,         \         „  .       ,     ,,   , 

metal    box    m    which    we  buy    Colgate  s       shavmg 

stick."    In  principle  it  is  a  light-proof  metal  box  into  which  a  liquid  may 

be  poured  without  opening  the  box  and  admitting  light. 

Both  hands  are  placed  in  a  light-proof  "  mufif " 
technic.  in  which  "  muff  "  the  film  packet  is  unwrapped,  the 

little  tank  opened,  the  films  placed  in  it,  and  the 
tank  closed.  The  tank  can  now  be  removed  from  the  "  muff  "  and  the 
films  inside  are  protected  from  light.  Pour  developing  solution  in  the 
tank,  leave  for  about  5  minutes,  pour  out  the  developing  solution.  Adjust 
a  screw  and  water  can  be  washed  through  the  tank.  Next  pour  in  the 
fixing  solution  and  leave  5  or  10  minutes.     Pour  out  the  fixer  and  wash 


MAKING  DENTAL  RADIOGRAPHS 


131 


with  water  again,  when  the  tank  may  be  opened  and  the  developed  film, 
the  negative,  observed. 

The   Van   Woert   tank   is   a  very  practical   device   for  the   general 
practitioner  of  dentistry  who  does  a  limited  amount  of  radiodontic  work. 


REFERRED    BY. 


DR.     HOWARD      I 

DENTAL     RADIOGRAPHER 
AND    DIAGNOSTICIAN 


11  W.   NORTH  Street 

Indianapolis 

Indiana 


DENTAL 

TRADE  "RADIOMOUNT"  MARK 


Fig.   120.      Radiomount   to   hold   dental   X-ray   negatives. 


on  films  only ;  and  in  offices  where  there  is  not  sufficient  space  available 
for  a  dark  room  and  where  even  a  daylight  developing  box  (Fig.  118) 
would  be  in  the  way,  the  little  tank  will  be  most  welcome.     (See  Fig.  E.) 


132 


DENTAL  RADIOGRAPHY 


f 


Fig.  121.     Negatives  mounted  between  glass  for  s-tudy  and  convenience  in  handling. 


miJc%nSffli  t  hardening  solution  is  made  by  dissolving  2 

Use  Suggested  by        °^-  ^*  potassium  carbonate  m  2  oz.  of  water.      1  his 

Dr.  Uan  Uloert.  should  be  filtered  and  kept  in  a  tightly  corked  bottle. 

After   removal   of  the  negative   from   the   fixing   solution   it   should   be 

v^ashed  in  watei   5  or  10  minutes  before  being  placed  in  the  hardener. 

Put  enough  of  the  hardening  solution  in  a  small  beaker  or  saucer  to 


MAKING  DENTAL  RADIOGRAPHS 


'^2>2> 


134 


DENTAL   RADIOGRAPHY 


^w^-  I  / 


'^a. 


%/. — ' 


-,  /■ ,  \ 


\    \ 


-'U 


Fig.  E.  Van  Woert  technic  illustrated.  Cut  No.  1  shows  the  hands  placed  in  the  muff.  Cut  No. 
2  shows  the  hands  inside  of  the  muff.  Cut  No.  3  shows  the  films  unwrapped  and  being 
placed  in  the  tank.  Cut  No.  4  shows  the  tank  closed  after  the  films  have  been  placed  in  it; 
the  tank,  with  the  films  in  it,  may  now  be  removed  from  the  muff. 


MAKING  DENTAL  RADIOGRAPHS  135 

cover  the  negative.  Leave  the  negative  in  the  hardener  three  minutes, 
when  it  may  be  removed  and  the  surplus  moisture  absorbed  by  blotting  it 
between  pieces  of  blotting  paper.  Wipe  the  emulsion  side  with  a  lintless 
napkin  such  as  the  Johnson  and  Johnson  mouth  napkin.  This  process  of 
hardening  and  immediate  drying  may  be  used  where  the  radiograph  is 
required  immediately.  For  such  negatives  as  are  to  be  preserved,  they 
should  be  washed  and  dried  in  the  usual  way. 


ndf  antagcs  of  Tilm 


The  advantages  of  the  small  dental  radiographs 
RadiAaraMh<  made  on  films  held  in  the  mouth  over  the  large  plate 

9    "''  ♦  radiographs  are :     ( i )    There  is  no  superimposition 

of  shadows,  and  therefore  a  clearer,  better  radiograph  can  be  made  on 
the  small  film.  (2)  The  patient  may  be  seated  in  the  dental  chair  while 
the  exposure  is  made  when  small  films  are  used.  (3)  The  time  of 
exposure  is  shorter  for  the  small  film.  (4)  Small  machines  with  which 
it  is  necessary  to  make  an  exposure  of  one  minute  or  longer  for  large 
plate  radiographs  will  make  a  good  dental  radiograph  on  a  film  held  in 
the  mouth  in  from  about  10  to  30  seconds.  (5)  A  compression  diaphragm, 
though  always  a  valuable  appliance,  is  not  so  essential  when  small  films 
are  used  as  it  is  when  large  plates  are  used.  (6)  The  negative  on 
celluloid  cannot  be  broken. 


flawantage  of  Plate 


The  great   advantage   of  the  large   plates   over 


Radioarauhs  ^^^   small   films   is   that   a    larger   field   can   be   pic- 


Scratcbing 
Tilm  nedatim. 


As  the  small  dental  films  lay  in  the  bottom  of 
the  trays,  during  the  process  of  development  and 
fixing  it  becomes  necessary  to  pick  them  up  re- 
peatedly. As  this  is  done,  the  finger  nail  sometimes  slips  off  the  edge, 
across  the  coated  surface  of  the  film,  so  spoiling  the  negative  or  at  least 
mutilating  it  in  a  very  undesirable  manner.  With  practice  one  may 
acquire  the  knack  of  picking  up  film  negatives  when  they  lay  flat  on  the 
bottom  of  the  tray  without  scratching  them,  but  my  assistant  has 
developed  a  very  simple  and  satisfactory  way  to  pick  them  up  which 
entirely  eliminates  the  probability  of  scratching  them. 

Wash  the  emulsion  ofif  an  old  negative,  or  better,  take  a  piece  of 
celluloid  thicker  than  that  used  to  make  films  and  fasten  a  hook  clip, 
such  as  is  illustrated  in  Fig.  119  to  hang  up  negatives,  to  it.  This  little 
device  my  assistant  calls  a  "scooter,"  which  seems  to  me  a  very  fitting 
name,  for,  holding  to  the  metal  clip  the  piece  of  celluloid  may  be 
"scooted"  under  films,  and  so  they  may  be  lifted  from  the  bottom  of 
trays  with  great  ease.  The  hooked  part  of  the  clip  may  be  placed  over 
the  edge  of  the  tray  so  the  "scooter"  is  not  misplaced  but  is  always  in 
position  ready  for  use  when  needed. 


CHAPTER  VI. 


Kexding  Hadiograpbs. 


Seeing  things  is  truly  a  mental  effort.  Though  an  object  or  shadow 
be  reflected  on  the  retina  of  the  eye,  it  is  not  "seen"  unless  it  has  an  effect 
upon  the  brain.  When  we  say,  "train  the  eye"  to  see  such  and  such  a 
thing,  we  mean  really,  train  the  mind — the  brain. 

To  correctly  read  a  radiograph,  to  see  all  there  is  in  it  to  be  seen, 
and  to  understand  it  to  mean  what  it  stands  for,  requires  experience  and 
an  intimate  knowledge  of  the  anatomy  and  pathology  of  the  parts  under 
observation.  Experience  is  an  important  factor.  Upon  looking  over  old 
negatives,  I  see  many  things  of  interest  in  them  now  which  I  did  not 
observe  a  year  ago. 

It  is  always  advisable  to  study  the  negative  in 

Tlluminating  preference  to  the  print.     Some  of  the  finest  details 

Boxes.  are  lost  in  the  print.     The  negative  may  be  held  up 

to  a  window  or  an  artificial  light,  or  it  may  be  placed 

in  an  illuminating  box  (Fig.  122)  for  observation. 

While  the  illuminating  boxes  on  the  market  are  suitable  for  studying 
large  plate  or  film  negatives,  they  are  needlessly  large  and  poorly  adapted 
for  studying  the  small,  dental,  film  negatives.  A  small  illuminating  box 
can  easily  be  made.  A  light-proof  box,  with  a  window  of  frosted  glass 
and  a  light  inside,  may  constitute  the  illuminating  box.  It  is  well  to  paint 
the  inside  of  the  box  white,  so  increasing  the  power  and  uniformity  of  il- 
lumination. With  the  negative  held  against  the  frosted  glass  of  the  window 
on  the  outside  and  the  light  lit  inside,  one  is  able  to  study  the  negative  to 
great  advantage.  Little  spring  steel  clips,  similar  to  the  ones  used  to  hold 
a  slide  or  a  microscope,  may  be  used  to  hold  the  negative  against  the 
frosted  glass  window. 

The  use  of  a  reading  glass  in  connection  with  an  illuminating  box 
"will  enable  one  to  observe  the  negative  to  the  best  possible  advantage. 

The   denser    the    part,  the  deeper  will  be  the 

CbC  Rdatioe  shadow  thrown  on  the  film,  and,  consequently,  the 

UalUCS  Of  Dense        more  transparent  the  negative  in  that  region.     Thus 

Jlreas  in  negatives,     in  the  negative,  metal  fillings,  posts  and  metal  crowns 

appear  as  transparent  areas;    gutta-percha,  cement, 

136 


READING   RADIOGRAPHS 


137 


enamel  and  porcelain  a  little  less  transparent ;  then  in  the  order  of  their 
respective  densities,  dentin,  bone,  gum  tissue,  and,  last,  the  cheek  appears 
— when  it  is  shown  in  the  negative  at  all — as  the  least  transparent  part, 
except  that  part  of  the  negative  on  which  the  X-Rays  have  fallen  directly 
without  anything  intervening  except  the  black  paper  of  the  packet.  The 
contrast  between  tooth  and  bone  tissue  is  very  marked.  Unfilled  canals 
and  pulp  chambers  appear  as  dark  streaks  and  areas  in  the  teeth.  Filled 
canals  and  pulp  chambers  appear  light.     Pulp  stones  appear  as  lighter 


Fig.    122.     An    Illuminating    Box. 


spots  in  the  dark  of  the  pulp  canal  or  chamber.  Abscess  cavities  appear 
as  dark  areas.  It  is  easy  to  distinguish  enamel  from  dentin,  and  the  peri- 
dental membrane  can  clearly  be  seen  as  a  dark  streak  following  the  out- 
line of  roots.  A  bit  of  calculus  in  the  peridental  membrane  will  appear 
as  a  light  spot.  This  calculus  must  be  on  either  the  mesial  or  distal  side 
of  a  root  to  be  seen.  It  could  not  be  radiographed  if  it  occurred  on  the 
buccal,  or  labial,  or  lingual. 

All  the  foregoing  may  be  seen  in  good  negatives, 
ncaatiV)C$    Prints        ^^^*  ^^^  ^^^^  cannot  be  seen  in  prints  and  half-tones. 
and  l)alf-tonc  I  recall  distinctly  having  read  an  article  on  Dental 

Reproductions.  Radiography  in  which  the  writer  printed  a  half-tone 

and  told  his  readers  to  ''observe  the  enamel,  the  den- 
tin and  the  peridental  membrane,"    The  writer  of  this  article  wrote  his 


138  DENTAL  RADIOGRAPHY 

paper  with  either  a  negative  or  a  good  print  before  him,  and  assumed 
that  all  he  saw  there  would  be  reproduced  in  the  half-tone.  It  was  not. 
The  half-tone  was  so  dark  that  all  detail  of  the  picture  was  lost,  and  the 
best  that  could  be  done  was  to  distinguish  between  bone  and  tooth  struc- 
ture. Let  us  stop  to  consider  the  steps  in  the  making  of  a  half-tone  pic- 
ture and  the  chance  for  the  loss  of  detail  is  apparent.  From  the  negative 
a  new  picture  is  made  on  photograph  paper,  the  print.  From  this  another 
picture  is  made  on  a  half-tone  plate,  and  from  this  the  half-tone  picture 
is  printed  on  paper  with  ink. 

The  finest  details  of  a  negative  cannot  be  shown  in  a  half-tone,  and, 
though  I  have  seen  many  prints  that  seemed  to  have  fully  as  much  detail 
as  the  negative,  there  is  usually  at  least  a  slight  loss  of  minute  detail  even 
in  well  made  prints. 

I  have  stated,  that  in  order  to  make  a  half-tone  picture  it  is  neces- 
sary first  to  make  a  photographic  print  or  picture  from  the  negative,  then, 
from  this,  to  make  the  half-tone  picture.  Thanks  to  the  efforts  of  Dr.  Ot- 
tolengui  and  his  co-workers,  I  am  able  to  print  a  half-tone  made  directly 
from  the  negative.  The  difference  in  the  appearance  of  a  half-tone  made 
from  a  negative  and  one  made  from  a  photographic  print  is  shown  in 
Fig.  123  (made  directly  from  the  negative)  and  Fig.  124  (made  from 
the  photographic  print,  but  reversed  in  the  process  for  easier  comparison). 

Densities — deep  shadows — we  have  seen  appear 
Relative  UalUCS  ^^  transparencies  in  the  negative.  The  print,  or  posi- 
Of  Shadows  in  tive,    is    the    opposite    of    the    negative.      Hence,    in 

Prints.  prints,  and  half-tones  made  from  them,  we  see  the 

deep  shadows  of  metal  fillings,  crowns  and  posts  ap- 
pearing very  dark,  gutta-percha,  cement,  enamel  and  porcelain  a  little 
less  dark,  and  so  on.  On  the  print,  filled  canals  appear  dark,  unfilled 
ones  light,  abscesses  appear  as  light  areas,  and  so  on,  always  the  opposite 
of  the  negative. 

In  order  to  avoid  confusion  of  the  right  and  left  sides  when  studying 
a  negative,  bear  the  following  in  mind :  When  looking  at  the  negative 
from  its  film  side  it  is  as  though  you  observed  the  part  radiographed 
from  the  position  occupied  by  the  tube  during  the  exposure.  When  look- 
ing at  the  negative  with  the  film  side  presenting  towards  the  light,  away 
from  the  eye,  it  is  as  though  you  observed  the  part  from  the  position  of 
the  film  during  exposure.  This  is  the  case,  granting  that  the  sensitive 
side  of  the  film  presented  toward  the  object  radiographed  at  the  time  of 
exposure,  a  condition  that  should  always  obtain  except  when  an  intensify- 
ing screen  is  used. 

If  the  technic  previously  given  is  followed,  and  the  sensitive  side  of 
the  film  or  plate  be  placed  so  as  to  present  toward  the  part  to  be  radio- 


READING  RADIOGRAPHS 


139 


140 


DENTAL  RADIOGRAPHY 


READING  RADIOGRAPHS  141 

graphed,  and  then  the  negative  placed  in  the  printing  frame  with  the 
sensitive  side  up  (this  must  be  done,  or  there  will  be  a  loss  of  detail) 
when  observing  prints,  it  is  as  though  one  looked  at  the  part  from  the 
position  of  the  film  or  plate  during  exposure. 

When  observing  half-tones  made  from  photographic  prints  it  is  the 
same  as  when  observing  the  prints  themselves,  unless  special  steps  have 
been  taken  in  the  process  of  making  the  half-tones  to  reverse  the  sides, 
as  was  done  in  Fig.  124.  When  observing  half-tones  made  from  nega- 
tives it  is  the  same  as  observing  negatives  from  the  film  side. 

When  looking  at  radiographs  made  directly  on  paper,  it  is  as  though 
you  observed  the  part  from  the  position  of  the  tube  during  exposure. 

How  to  mark  negatives  is  a  subject  that  has 

markina  caused  the  use  of  a  great  deal  of  perfectly  good  paper 

negatives.  and  ink.     After  trying  several  methods,  I  no  longer 

attempt  to  mark   my   negatives,   but  place  them  in 

envelopes  and  mark  the  envelopes  as  desired.     The  Lumiere  Dry  Plate 

Co.  print  the  following  outline  on  the  backs  of  their  envelopes : 

No 

Name 

Address    

Date    

Case    

Tube  used  

Exposure  

Distance  of  Tube  from  Plate 

Developer    

Referred   by   Doctor 

Remarks    

I  have  lately  heard  of  an  "X-Ray  ink"  for  marking  negatives,  but 
have  been  unable  to  procure  any.  The  desired  markings  are  placed  on 
the  envelopes  or  black  paper  covering  the  plate  or  film,  the  marking  being 
done  on  the  side  of  the  envelope  or  black  paper  presenting  toward  the 
sensitive  side  of  the  plate  or  film,  so  that  when  the  exposure  is  made  the 
ink  markings  are  between  the  source  of  the  rays  and  the  sensitive  side  of 
the  plate  or  film.  This  ink  must,  I  think,  contain  some  salt  of  lead  or 
bismuth,  for  the  X-Rays  penetrate  it  very  poorly,  and  consequently  there 
is  a  shadow  cast  on  the  negative. 

My  objection  to  marking  small  dental  films  in  this  manner  is  that 
occasionally  the  shadow  of  the  markings  will  occur  in  such  a  place  in  the 
radiograph  as  to  spoil  the  picture.  The  older  methods  of  placing  wires 
bent  to  form  the  figures  or  letters  for  marking,  or  a  stencil  of  sheet  metal, 
between  the  source  of  rays  and  the  plate,  is  highly  unsatisfactory,  so  far 
as  their  application  to  the  marking  of  small  dental  radiographs  is  con- 


t42 


DENTAL  RADIOGRAPHY 


cerned.  After  the  negative  is  made,  markings  may  be  scratched  in  the 
film.  But,  as  I  said  before,  no  system  of  marking  the  negative  itself  is 
as  satisfactory  as  marking  the  envelope  in  which  it  is  kept. 

One  of  the  most  unfortunate  limitations  of  the 

Perspective.  radiograph  is  that  it  lacks  perspective.    For  example, 

though  we  are  able  to  observe  the  exact  mesio-distal 


Fig.    135.      (Reduced    one-half.) 


position  of  an  impacted  tooth,  we  are  unable  to  determine  its  bucco-  or 
labio-lingual  position,  with  any  degree  of  accuracy. 

The  closer  the  object,  which  is  being  radiographed,  is  to  the  film 
during  exposure,  the  clearer  the  resulting  shadow  will  be.  Thus,  for 
example,  if  an  impacted  cuspid  lay  lingually  to  the  other  teeth,  and  the 
film  were  held  inside  the  mouth  as  usual,  the  detail  in  the  picture  of  the 
cuspid  would  be  a  little  greater  than  the  detail  in  the  other  teeth.  If  the 
cuspid  lay  to  the  labial, — farther  away  from  the  film. — detail  in  it  would 
be  less  than  in  the  other  teeth.  But,  on  the  whole,  this  method  of  deter- 
mining bucco-  or  labio-hnq-ual  location  is  unreliable. 


READING  RADIOGRAPHS 


143 


While  I  agree  with  Dr.  C.  H.  Abbot,  of  BerHn,  who  has  done  some 
writing  and  experimental  work  to  prove  that  radiographs  are  not  totally 
lacking  in  perspective,  yet  I  do  declare,  from  the  standpoint  of  their  prac- 
tical application  to  dentistry,  that  they  are  simply  shadow  pictures.  And 
let  me  here  warn  you  that  like  all  shadows,  X-Ray  pictures  are  often  ex- 
tremely misleading;  one  might  say,  for  the  word  seems  to  fit  so  well, 
treacherous.  To  eliminate  the  chance  of  misreading,  because  of  distor- 
tion of  the  radiograph,  it  is  often  expedient  to  make  several  pictures  of 
the  same  part  or  field,  changing  the  pose.     Even  this,  however,  does  not 


Fig.    126.     A  dental   fluoroscope.        Fig.    127.      Shadows   of   teeth   cast   on   the    fluoroscope. 


preclude  the  possibility  of  misinterpretation.  To  correctly  read  radio- 
graphs, a  man  must  be,  not  only  a  student  of  radiography,  anatomy,  his- 
tology and  pathology,  but  he  must  have  and  use  that  gift  of  the  gods — 
common  sense.  He  must  not  jump  at  conclusions,  and  he  should  ever 
regard  the  radiograph  as  a  shadow  picture,  liable  to  all  the  apparent  mis- 
representations of  shadows. 

A  study  of  Fig.  125  will  convince  anyone  of  the  lack  of  perspec- 
tive in  at  least  some  radiographs.  One  is  unable  to  determine,  from 
observing  this  radiograph,  whether  the  coin  pictured  is  in  the  flesh  of 
the  hand,  on  the  back  of  the  hand,  or  in  the  palm  of  the  hand.  Likewise, 
from  simple  observation,  it  is  impossible  to  tell  whether  the  needle  is  in, 
on,  or  under  the  hand.  By  deduction,  we  may  come  to  this  conclusion : 
The  coin  was  nearer  the  plate,  during  its  exposure,  than  the  needle,  be- 
cause the  outline  of  the  coin  is  much  clearer  than  that  of  the  needle,  and 
other  things  remaining  equal,  the  closer  the  object  being  radiographed  is 
to  the  plate,  the  clearer  its  shadow  will  be.     Still  we  cannot  determine 


144  DENTAL  RADIOGRAPHY 

the  exact  location  of  either  needle  or  coin.  We  know  only  that  the  coin 
was  somewhat  closer  to  the  plate,  during  its  exposure,  than  the  needle. 
That  is  all. 

The  coin  lay  under  the  hand  on  the  envelope  holding  the  plate,  the 
needle  on  the  back  of  the  hand,  when  the  exposure  for  Fig.  125  was  made. 

To  overcome  the  fault  of  the  lack  of  perspective 
Stereoscopic  and,  to  some  extent,  the  distortion  in  radiographs, 

KadiOgrapby.  one  must  resort  to  stereoscopic  radiography. 

Stereoscopic  radiography  is  the  science  and  art 
of  making  radiographs,  which,  when  observed  through  a  stereoscope,  have 
perspective.  The  technic  of  making  stereoscopic  radiographs,  together 
with  a  discussion  of  their  value  and  efficiency,  will  be  dealt  with  at  some 
length  in  a  subsequent  chapter. 

A  work  of  this  kind  would  be  incomplete  with- 
Dental  out  some  mention  of   the   dental  fluoroscope.     The 

TlUOroscopC.  simplest    and    most    efficient   dental    fluoroscope   has 

been  designed  by  Dr.  Tousey  (Fig.  126).  Like 
all  fluoroscopes,  this  one  depends  on  calcium  tungstate,  or  platino-barium 
cyanide,  for  its  action.  A  disc  of  cardboard,  coated  on  both  sides  with 
either  of  the  above  named  chemicals,  is  placed  between  two  discs  of 
transparent  glass,  and  the  glasses  and  cardboard  (or  fluorescent  screen, 
for  the  cardboard  becomes  a  fluorescent  screen  when  it  is  coated  with 
calcium  tungstate  or  platino-barium  cyanide)  held  together  by  means  of 
a  circular  band  of  metal.  A  handle  now,  and  we  have  a  dental  fluoro- 
scope, the  screen  protected  against  moisture,  and  either  side  of  it  may 
be  used. 

To  use  the  fluoroscope,  the  operating  room  should  be  dark.  It  is 
best  that  the  operator  remain  in  this  darkened  room  for  some  time  until 
his  eyes  become  accustomed  to  the  darkness  before  making  the  exposure. 
Hold  the  fluoroscope  inside  of  the  mouth,  and  have  the  tube  placed  so 
that  the  X-rays  will  pass  through  the  part  to  be  observed,  and  strike  the 
fluoroscope.  Fig.  127  shows  the  fluoroscope  and  a  shadow  of  the  teeth 
thrown  on  it. 

The  disadvantages  of  the  fluoroscope  are : 

1.  The  operator  must  expose  himself  to  the  actions  of  the  X-rays. 

2.  Either  the  time  for  observation  must  be  made  very  short,  or  both 
operator  and  patient  must  be  exposed  to  the  rays  unnecessarily  and 
dangerously  long. 

3.  The  picture  on  the  fluoroscope  lacks  detail. 

4.  No  record  of  the  case,  other  than  a  mental  picture,  can  be  kept', 


READING  RADIOGRAPHS  145 

while  a  negative  may  be  referred  to  as  often  as  expediency  or  neces- 
sity demands. 
5.      From  an  educational  standpoint,  the  fact  that  prints,  lantern  slides 
and  half-tones  can  be  made  from  negatives  is  a  great  advantage. 
To  learn  to  eat  olives,  one  must  eat  them,  so  I  am  told.     To  learn 
to  read  radiographs,  one  must  read  them,  and  so  we  pass  to  the  next 
chapter,  wherein  we  shall  study,  in  a  practical  way,  the  reading  of  radio- 
graphs. 


For  further  consideration  o£  reading,  or  interpreting  radiographs,  see  Appen- 
dix,  Chapter  VI. 


CHAPTER  VII. 

ZM  Uses  of  the  Ktidiosrapb  in  Dentistry. 

The  use  of  the  radiograph  in  the  practice  of  modern  dentistry  is 
almost  hmitless.  Some  of  the  cases  hereinafter  mentioned  are  such  as 
the  general  practitioner  of  dentistry  might  not  be  called  upon  to  diagnose 
or  treat  oftener  than  once  oi"  twice  in  a  lifetime,  if  at  all.  But  by  far 
the  greater  number  of  them  are  such  as  are  met  repeatedly  in  the  prac- 
tice of  dentistry. 

The  radiograph  may  be  used  in  the  following  cases:  (i)  In  cases 
of  delayed  eruption,  to  determine  the  presence  or  absence  of  the  un- 
erupted  teeth.  (2)  In  cases  where  deciduous  teeth  are  retained  long 
after  the  time  when  they  should  have  been  shed,  to  learn  if  the  succe- 
daneous  teeth  be  present.  (3)  To  learn  if  the  roots  of  children's  teeth 
be  fully  formed.  (4)  To  determine  whether  a  tooth  be  one  of  the  pri- 
mary or  secondary  set.  (5)  To  determine  when  to  extract  temporary 
teeth.  (6)  To  show  the  orthodontist  when  he  may  move  the  coming 
permanent  teeth  by  moving  the  deciduous  teeth.  (7)  To  observe  moving 
teeth.  (8)  In  cases  of  supernumerary  teeth.  (9)  In  cases  of  impacted 
teeth  as  an  aid  in  extraction.  (10)  To  determine  the  number  of  canals 
in  some  teeth.  (11)  As  an  aid  in  filling  the  canals  of  teeth  with  large 
apical  foramina.  (12)  To  learn  if  canals  are  open  and  enlarged  to  the 
apex  before  filling  and  to  observe  the  canal  filling  after  the  operation. 
(13)  To  determine  whether  an  opening  leading  from  a  pulp  chamber 
be  a  canal  or  a  perforation.  (14)  In  cases  of  pulp  stones.  (15)  In 
cases    of    secondary    dentine    being    deposited    and    pinching    the    pulp. 

(16)  To    learn    if    the    filling    in    the    crown    encroaches    on    the    pulp. 

(17)  In  cases  of  teeth  with  large  metal  fillings  or  shell  crowns  which 
do  not  respond  to  the  cold  test,  to  learn  if  the  canals  are  filled.  (18) 
To  learn  if  apical  sensitiveness  is  due  to  a  large  apical  foramen  or  an 
unremoved,  undevitalized  remnant  of  pulp.  (19)  In  cases  of  chronic 
pericementitis  ("lame  tooth").  (20)  In  cases  of  alveolar  abscess  to  de- 
termine which  tooth  is  responsible  for  the  abscess.  (21)  In  cases  of 
alveolar  abscess  to  determine  the  extent  of  the  destruction  of  tissue — 
bony  and  tooth.  (22)  In  cases  of  alveolar  abscess  to  learn  how  many 
teeth  are  involved.  (23)  In  cases  of  abscess  of  multi-rooted  teeth  to 
learn  at  the  apex  of  which  root  the  abscess  exists.     (24)   In  cases  of 

146 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY     i^y 

abscesses  of  crowned  teeth  to  learn  whether  the  canals  are  properly  filled. 
(25)  As  an  aid  in  differential  diagnosis  between  chronic  alveolar  abscess 
and  pyorrhea  alveolaris.  (26)  To  observe  destruction  of  tissue  due  to 
pyorrhea  alveolaris.  (27)  In  cases  of  pericemental  abscess.  (28)  In 
cases  of  persistent  suppuration  which  does  not  yield  to  the  usual  treat- 
ment. (In  fact  in  all  cases  that  do  not  yield  promptly  to  the  usual 
course  of  treatment.)     (29)    To  observe  the  course  of  a  fistulous  tract. 

(30)  To  observe  the  field  of  operation  before  and   after   apicoectomy. 

(31)  To  locate  foreign  bodies,  such  as  a  broach  in  the  pulp  canal  or 
tissues  at  the  apex  of  a  tooth ;  a  piece  of  wooden  toothpick  in  the  peri- 
dental membrane,  etc.  (32)  To  determine  the  presence  or  absence  of 
a  bit  of  root  imbedded  in  the  gum  tissue.  (33)  To  diagnose  fracture 
of  a  root.  (34)  To  observe  the  size  and  shape  of  the  roots  of  teeth  to 
be  used  in  crown  and  bridgework.  (35)  As  an  aid  and  safeguard  when 
enlarging  canals  for  posts.  (36)  To  examine  bridges  about  which  there 
is  an  inflammation.  (37)  To  observe  the  field  before  constructing  a 
bridge.  (38)  To  observe  planted  teeth.  (39)  In  cases  of  cementoma. 
(40)  In  cases  of  bone  "whorls."  (41)  To  locate  stones  (calculi)  in  the 
salivary  ducts  or  glands.  (42)  In  cases  of  bone  cysts.  (43)  In  cases 
of  dentigerous  cysts.  (44)  In  cases  of  tumor,  benign  or  malignant.  (45) 
To  observe  anomalous  conditions,  such  as  the  fusion  of  the  roots  of  two 
teeth  for  example.  (46)  To  observe  the  location  and  extent  of  a  necrotic 
or  carious  condition  of  bone.  (47)  To  diagnose  antral  empyema.  (48) 
To  observe  size,  shape  and  location  of  the  antrum  as  an  aid  in  opening 
into  it.  (49)  To  locate  foreign  bodies,  such  as  tooth  roots  or  broaches, 
in  the  antrum.  (50)  To  observe  cases  of  luxation.  (51)  In  cases  of 
fracture  of  the  jaw  before  and  after  reduction.  (52)  In  cases  of  anky- 
losis of  the  temporo-mandibular  articulation  or  the  joint  formed  by  the 
tooth  in  the  jaw.  (53)  To  observe  the  field  of  operation  before  and  after 
resection  of  the  mandible.  (54)  In  all  cases  of  facial  neuralgia  with 
an  obscure  etiology.  (55)  To  observe  the  inferior  dental  canal.  (56)  In 
cases  of  Ludwig's  angina.  (57)  In  cases  of  insomnia,  neurasthenia, 
insanity*  and  kindred  nervous  disorders.  (58)  In  cases  of  periodic 
headaches.  (59)  In  cases  of  facial  gesticulatory  tic  (spasmodic  twitch- 
ing of  a  set  of  the  facial  muscles).  (60)  To  allay  the  fears  of  a 
hypochondriac.  (61)  In  cases  where  the  patient  cannot  open  the  mouth 
wide  enough  for  an  ocular  examination.  (62)  In  research  work  to 
study  osteology,  the  development  of  teeth,  action  of  bismuth  paste,  bone 
production  and  destruction,  changes  occurring  in  the  temporo-mandibular 
articulation  when  jumping  the  bite,  blood  supply  to  parts,  resorption  of 


*Dr.   Upson — Cleveland. 


148  DENTAL  RADIOGRAPHY 

teeth  and  the  causes  for  it,  etc.  (63)  As  a  record  of  work  done.  (64)  In 
cases  of  hidden  dental  caries. 

It  is  with  a  mingled  feeling  of  enthusiasm  and  misgiving  that  I 
now  attempt  to  illustrate  the  above  named  uses  of  the  radiograph.  It 
is  not  reasonable  to  hope  that  half-tones  will  show  all  that  can  be  seen 
in  negatives.  As  a  result,  things  may  be  mentioned  in  the  text  that 
cannot  be  observed  in  the  half-tones ;  but,  be  assured,  all  clinical  factors 
mentioned  in  the  text  were  observable  in  the  original  radiographs. 

Thanks  to  the  help  rendered  by  many  radiographers,  whose 
names  appear  beneath  the  half-tones,  and  the  practitioners,  whose  names 
are  mentioned  in  the  text,  I  will  be  able  to  illustrate  almost  all  of  the 
above  enumerated  uses. 

In  describing  cases  which  have  not  come  under  direct  personal 
observation  there  is,  of  course,  considerable  liability  to  mistakes.  I  ask 
my  readers  to  bear  this  in  mind. 

It  shall  be  my  policy  to  print  as  few  radiographs  as  possible  to  fully 
demonstrate  the  different  uses.  For  example,  I  could  print  hundreds 
of  different  radiographs  illustrating  the  use  "  in  cases  of  delayed  eruption 
to  determine  the  presence  or  absence  of  the  unerupted  teeth."  But  only 
a  few  will  be  used,  because  that  is  all  that  is  necessary  to  demonstrate 
the  value  of  the  radiograph  in  such  cases,  and  to  use  more  would  be 
superfluous  in  a  work  of  this  kind. 


1.   In  0a$c$  of  Delayed  eruption  to  Determine  the  Presence  or  Absence  of  tbe 

Unerupted  Ceetb 

Upper,  permanent  laterals  missing  in  the  mouth 

Tig.  12$  of  a  girl,  eighteen  years  of  age.     Spaces  between  the 

centrals,  and  the  centrals  and  cuspids.     In  this  case 

the  deformity  seemed  particularly  distressing  because,  save  for  the  spaces 

between  her  teeth,  the  young  lady  was  positively  beautiful. 

A  radiograph  (Fig.  128)  was  made  and  shows  that  the  laterals  are 
not  impacted  in  the  upper  maxilla.  It  therefore  became  necessary  to 
move  the  centrals  together  and  construct  a  bridge.  Had  the  laterals 
been  present  in  the  maxilla,  and  space  made  for  them  by  moving  the 
centrals  together,  they  would  probably  have  erupted  into  their  places. 
Had  they  not  erupted  after  space  had  been  made  for  them  the  tissues 
covering  them  could  have  been  dissected  away,  holes  drilled  into  the 
teeth,  little  hooks  cemented  into  these  holes  and  the  teeth  elevated 
orthodontically. 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY     149 

When  there  seems  to  be  a  congenital  absence  of 
Tifl.    129.  ^  tooth  from  the  jaw  it  is  expedient — which  is  ex- 

pressing it  mildly — to    use    the    radiograph    before 
constructing  and  setting  a  bridge.   Failure  to  do  this  might  result  in  what 


Fig.   128.      Congenital  absence  of  the   upper  lateral   incisors.     Age  of  patient,   eighteen   years. 


Fig.  129.  Fig.  130. 

Fig.   129.      Bridge  from  central  to  first  bicuspid.      Unerupted  cuspid.     The   arrow   points   to   a   bit 

of   tooth    root.      (Radiograph   by    Ream   of    Chicago.) 

Fig.   130.      An  upper  cuspid  in  the  place   of  the  lateral.      A   temporary   cuspid  in   the  place   which 

should  be  occupied  by  permanent  cuspid.     The  lateral  missing  from  the   jaw. 

is  shown  in  Fig.  129 — an  unerupted  cuspid  covered  with  a  bridge.  Such 
a  condition  as  this  may  or  may  not  cause  local  inflammation,  neuralgia, 
or  any  of  a  series  of  inflammatory  and  nerve  disorders.  In  this  case  the 
bridge  covers  not  only  an  unerupted  cuspid,  but  also  a  bit  of  tooth  root. 

In  a  case  presented  to  me  an  upper  permanent 

"  Tl8.    130.  cuspid  was  seen  occupying  the  place  of  the  lateral 

incisor,  and  a  temporary  cuspid  was  in  the  space 


I50 


DENTAL  RADIOGRAPHY 


Fig.    131. 


Fig.   132. 


Fig.    131. 


Congenital   absence   of   the   uppei-   second   bicuspid.      Observe   the    orthodontia    appliance 
in   position.      (Radiograph    by    Lev/is    of    Chicago.) 
Fig.   132.      Delayed  eruption  of  an  upper   second  bicuspid.     The   orthodontia   appliance   in   position 
is  being  used  to  make  space  in  the  arch  for  the  delayed  tooth.    (Radiograph  by  Lewis  of  Chicago.) 


Fig.  133.     A  badly  impacted  lower  second  bicuspid,  with  no  space  at  all  for  it  in  the  dental  arch. 
(Radiograph   by  Pancoast   of   Philadelphia.) 


THE   USES  OF   THE  RADIOGRAPH  IN  DENTISTRY   151 

which  should  have  been  occupied  by  the  permanent  cuspid.  A  radio- 
graph was  made  (Fig.  130)  to  locate  the  missing  lateral.  It  was  not 
present  in  the  jaw.  Though  I  am  not  absolutely  sure  of  this,  I  never- 
theless feel  quite  certain  that  the  permanent  lateral  was  mistaken  for  a 
temporary  tooth  and  extracted  when  the  patient  was  about  seven  or 
eight  years  old— a  mistake  which  could  not  have  happened  had  the  dentist 
used  radiographs. 


Fig.  131  proves  the  absence  of  a  second  bicus- 

Tlfls.  131  and  132.        pid  and  shows  that  bridgevvork  must  be  resorted  to, 

to  fill  the  space.      Fig.    132  discloses  the  presence 

of  a  second  bicuspid  and  shows  that  it  will  not  be  necessary  to  make  a 

bridge.    As  they  appeared  before  radiographs  were  taken  the  cases,  from 

which  Figs.  131  and  132  were  made,  were  similar. 

Fig.     133,    a    case    of    Dr.    Cryer's,    shows    a 
TI9.  133.  badly  impacted  lower  second  bicuspid  with  no  space 

at  all  for  it  in  the  dental  arch. 

With  the  exception  of  the  third  molars  no  teeth 
Tig.  134.  are  so  liable  to  be  delayed  in  their  eruption  as  the 

upper  cuspids.  For  this  reason,  when  making  a 
radiograph  to  determine  the  presence  or  absence  of  an  unerupted  upper 
cuspid  or  an  upper  or  lower  third  molar,  I  feel  tolerably  sure,  before  I 
make  the  picture,  that  the  tooth  will  be  found  somewhere  in  the  jaw. 
When  the  missing  tooth  is  a  central,  lateral,  bicuspid,  or  lower  cuspid,  I 
am  in  doubt  as  to  what  to  expect.  My  experience  teaches  me  that  when 
these  teeth  are  missing  they  are  just  as  likely  to  be  entirely  absent  from 
the  jaw  as  present  in  it,  and  simply  unerupted.  So  far,  I  have  never  seen 
either  long  delayed  eruption  or  congenital  absence  of  the  first  or  second 
molars.* 


*Since  the  first  publication  of  the  above,  Dr.  Ottolengui  has  reported  two  in- 
teresting cases  (Items  of  Interest,  February  19,  1913),  from  which  record  I  quote 
in  part,  as  follows : 

"Very  shortly  after  Dr.  Raper  had  published  the  fore- 
going statement,  that  up  to  that  time  he  had  not  seen  a  case 
IniSSilig  wherein  first  or  second  molars  were  congenitally  absent,  a 

Tirst  lHolar  little  girl  patient  of  mine  came  in  for  her  periodical  exami- 

nation, and  I  noted  that  since  her  previous  visit  she  had 
erupted  three  first  permanent  molars,  but  the  fourth  had  not  appeared.  I  imme- 
diately began  to  wonder  whether  or  not  I  was  about  to  discover  an  authentic  case 
of  congenital  absence  of  a  first  molar.     I  say  authentic,  because  in  records  of  this 


152  DENTAL   RADIOGRAPHY 

kind  it  is  not  always  that  one  may  be  sure  that  the  history  is  authentic.  But  in 
this  particular  case  there  can  be  no  doubt.  The  child  was  the  sister  of  another  girl 
in  my  care  and  had  been  under  my  observation  since  she  was  four  years  of  age. 
I  have  casts  of  her  mouth  at  the.  age  of  five,  which  show  the  primary  denture 
complete.  I  may  add  also  that  there  never  had  nor  has  been  any  caries,  and  con- 
sequently there  was  no  possibility  that  a  molar  had  been  extracted,  a  suspicion 
always  warranted  when  we  find  a  first  molar  absent  from  the  mouth  of  an  adult. 
An  ordinary  small  mouth  radiograph  was  made,  and  while  it  did  not  disclose  the 
shadow  of  a  molar,  neither  did  it  satisfactorily  show  what  really  existed.  I  there- 
fore determined  to  have  a  large  radiograph  made,  so  that  we  might  have  a  picture 
of  the  entire  bone. 


Fig.  A. 

Odontoma  in  region  which  should  normally  be  occupied  by  lower  first  molar.      Patient  8  years 
eld.     Malposed  lower  second  molar.      (Radiograph  by  Schamberg,  of  New  York  City.) 


"  The  patient  was  sent  to  Dr.  M.  I.  Schamberg,  who  made  radiographs  of  both 
sides  of  the  mandible,  that  we  might  compare  them.  The  radiographs  are  repro- 
duced in  Figs.  A  and  B.  My  surprise  may  be  imagined  when  I  found  that  in  the 
region  which  should  have  been  occupied  by  the  second  bicuspid  and  the  first  molar, 
there  was  a  well-defined  composite  odontoma.  And  perhaps  even  more  astonishing 
is  the  position  of  the  molar  lying  distally  of  the  tumor.  Whether  this  tooth,  which 
is  seen  lying  horizontally  in  the  bone,  is  the  first  molar  or  the  second  molar,  is  a 
question  that  has  been  raised  by  an  orthodontist  of  national  reputation,  a  man  of 


THE   USES  OF  THE  RADIOGRAPH  IN  DENTISTRY   153 

keen  judgment  and  well  informed  as  to  tooth  forms.  While  I  am  willing  to  admit 
that  this  looks  more  like  a  first  than  a  second  molar,  especially  when  we  compare 
with  the  normal  side  (Fig.  B),  still  I  very  much  doubt  that  it  is  the  first  molar. 
The  odontoma  is  more  apt  to  be  a  composite  of  the  bicuspid  and  first  molar.  But 
in  any  event,  interesting  as  this  case  is,  it  cannot  be  entered  in  the  literature  as  a 
record  of  congenital  absence  of  a  first  permanent  molar,  because  that  tooth  is 
either  in  the  bone  or  else  is  included  in  the  odontoma,  whereas  by  "  congenital 
absence"  I  understand  to  be  meant  complete  non-existence. 


Fig.  B. 

Same   patient   as   for   Fig.   A,    opposite   side,   conditions   normal. 

New  York  City.) 


(Radiograph   by   Schamberg,    of 


"  The   second   case   which   I   am   permitted   to   report  is 
fniSSSing  from  the  practice  of  Dr.  Thaddeus   P.  Hyat,  and  is  in  the 

Second   molars.  hands  also  of  Dr.  George  B.  Palmer  for  orthodontic  treat- 

ment. The  patient  is  a  boy  of  fourteen,  and  we  are  assured 
that  no  permanent  teeth  have  been  extracted,  yet  no  less  than  thirteen  permanent 
teeth  are  missing.  In  the  upper  jaw  the  absent  teeth  are :  both  lateral  incisors, 
three  bicuspids,  both  second  molars  and  both  third  molars,  a  total  of  nine  teeth 
(note  that  both  upper  laterals  are  absent,  while  both  upper  cuspids  are  present). 
In  the  lower  jaw  the  following  teeth  are  absent:  the  first  bicuspid  and  the  third 
molar  on  the  right  side  and  the  second  bicuspid  and  the  third  molar  on  the  left  side. 


154 


DENTAL   RADIOGRAPHY 


"  Figs.  C  and  D  are  radiographs  of  the  two  sides  of  the  head.  In  the  upper 
the  first  molars  are  easily  distinguished,  but  there  are  no  evidences  of  the  second 
and  third  molars.  In  the  mandible  the  third  molars  are  absent,  but  the  other  four 
molars  are  present,  though  in  one  case  the  crown  has  been  lost  by  caries.  Con- 
sidering the  boy's  age,  this  seems  to  be  an  authentic  record  of  congenital  absence 
of  two  second  upper  molars,  and  of  all  four  third  molars,  as  the  extraction  of  any 
of  these  teeth  could  not  have  been  forgotten. 


Fig.  C. 


Patient's  age  13.     Right  side. 


Missing  teeth:  Upper  bicuspids,  second  and  third  molars.     Lower 
first  bicuspid  and  third  molar. 


"  Dr.  Hyat  has  kindly  asked  another  patient  of  his  to 

lDi$$in9  f\V$t,  call  at  my  office  that  I  might  examine  a  very  similar  case. 

Second  and  in  this   instance  the   patient  is   a   woman   about  thirty-five 

€bird  I1l0l(lt*$.  years  of  age.     She  is  a  highly  cultured  person  engaged  in 

the  editorial  department  of  one  of  our  leading  magazines. 

She  is  quite  positive  that  the  only  tooth  she  ever  had  extracted  was  one  lower  first 

molar.     If  this  be  true  she  has  fourteen  teeth  congenitally  absent  as  follows :     In 

the  upper  jaw   the   missing  teeth   are   the   two   lateral   incisors,   the    first,    second 

and  third  molars  on  the  left  side,  and  the  second  and  third  molars  on  the  right 

side.     In  the  lower  jaw  the  missing  teeth  are  the  second  bicuspid  and  all  three 


THE    USES   OF   THE  RADIOGRAPH  IN  DENTISTRY    155 

Fig.  134  is  representative  of  a  class  of  delayed  eruption  that  is  most 
common.  I  could  print  hundreds  of  radiographs  of  such  cases.  Fig. 
123  was  a  beautiful  example.  The  age  of  the  patient  in  this  particular 
case  (Fig.  134)  was  some  months  over  fourteen.  The  radiograph  was 
made  for  an  orthodontist  who  was  just  beginning  treatment  of  the  case. 
There  was  no  evidence  of  the  presence  of  the  cuspid  and  no  room  for 
it  to  erupt.     When  the  arch  was  broadened  and  space  made  for  it  the 


Fig.  D. 

Same  patient  as  for  Fig.   C,   left  side.      Missing  teeth:   Upper  second  bicuspid,   second   and   third 
molars.      Lower    second    bicuspid    and    third    molar.       The    roots    only    of    the    lower    first    molar 

remain. 


cuspid  erupted.     It  required  some  mechanical  guidance  to  make  it  come 
into  its  exactly  proper  position. 


molars  on  the  right  side,  and  both  bicuspids  and  the  third  molar  on  the  left  side 
Again  we  have  the  upper  laterals  missing,  and  the  upper  cuspids  present. 

"  In  this  mouth  we  have  the  strange  anomaly  of  three  molars  missing  from 
the  upper  jaw  on  the  right  side,  and  three  molars  missing  from  the  lower  jaw  on 
the  left  side.  Enumerated  in  full  the  absent  molars  were  all  four  of  the  third 
molars,  three  of  the  second  molars  and  two  of  the  first  molars." 


156  DENTAL   RADIOGRAPHY 

The  mere  making  of  space  for  them  in  the  arch  will  usually  result 
in  the  eruption  of  unerupted  teeth,  unless  they  are  malposed.  If,  after 
space  is  made,  the  tooth  does  not  move,  the  gum  and  process  over  it 
should  be  slit  surgically.  If  this  does  not  suffice  to  induce  eruption, 
the  soft  parts  and  process  must  be  cut  away,  and  sometimes  it  may  be 
necessary  to  resort  to  the  use  of  orthodontia  appliances  to  assist  erup- 
tion, as  formerly  suggested. 

In  handling  cases  of  unerupted  teeth  it  should  constantly  be  borne 


Fig.  134.     Age  of  patient,  fourteen.      An  unerupted  malposed  cuspid.      No   room   for  it   in   the 

dental  arch.      Observe  the  tipping  of  the  lateral,  which   is  probably  due  to   the  pressure   of  the 

cuspid  against  the  apex  of  its  root. 


in  mind  that  it  is  an  almost  invariable  rule  that  unerupted  teeth  move 
only  in  the  direction  in  which  they  point ;  i.  e.,  "  In  a  line  with  their  long 
axis."  Thus  an  unerupted  tooth  must  be  headed  right,  or  pointed  right, 
to  induce  it  to  erupt. 

When  radiographing  cases  of  delayed  eruption  we  may  expect  to 
find  (i)  the  tooth  present  in  the  jaw — Fig.  134;  (2)  the  tooth  missing 
from  the  jaw — Fig.  131 ;  (3)  an  odontoma  in  the  place  of  the  tooth — 
Fig.  A ;  (4)  an  odontoma  or  supernumerary  tooth  preventing  eruption 
— Figs.  263  and  264. 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY     157 

2.   Tn  0a$e$  lUbcre   Deciduous  teeth  are  Retained  Cong  :Hfter  the  time  lUben 

they  Should  I)ave  Been  Shed,  to  Cearn  if  the  Succedaneous 

teeth  be  Present. 

Case — Girl,    age     seventeen,     large     cavity    in 

Tig.  135.  upper,  second,  deciduous  molar.    Whether  to  fill  this 

tooth  or  extract  it  depended  on  whether  there  was 

a  second  bicuspid  to  take  its  place  in  case  of  extraction.     It  was  not  at 

all  loosened  and  there  was  no  visible  evidence  of  the  presence  of  the  suc- 


Fig.  135. 


Fig.   136. 


Fig.  135.     Age  of  patient,  seventeen.     Retained  upper,  second,  temporary  molar.     The  radiograph 

sliows  that  the  second  bicuspid  is  present  in  the  jaw. 

Fig.    136.      Age   of  patient,   twenty-one.      Retained   lower,    second,    temporary   molar    with    a    large 

cavity  in   the  crown   of  the   tooth   and   the   roots   almost   entirely   resorbed,    despite    the    fact   that 

there  is  no   oncoming  second  bicuspid. 


ceeding  bicuspid.  Fig.  135,  however,  shows  the  bicuspid  to  be  present. 
The  half-tone  may  not  do  so,  but  the  negative  now  before  me  has  per- 
spective enough  for  me  to  see  that  the  bicuspid  is  being  deflected  toward 
the  lingual.  The  deciduous  tooth  was  extracted  and  the  bicuspid  erupted 
promptly. 

Case — young  man,  age  twenty-one,  lower,  sec- 
Tifl.    136.  ond,  deciduous  molar  with  pulp  exposed.     Question : 

Should  the  tooth  be  treated,  filled  and  retained  in 
the  mouth,  or  extracted  to  make  room  for  the  second  bicuspid?  Fig. 
136  demonstrates  the  futility  of  attempting  to  treat  the  tooth — its  roots 
are  almost  entirely  resorbed  despite  the  fact  that  there  is  no  succedaneous 
tooth  in  the  jaw — and  shows  also  that  there  is  no  bicuspid  to  take  its 
place.     Extraction  and  bridgework  are  indicated'. 

Fig.    137    shows    two    retained    temporary    up- 
Tig.  137.  per  cuspids  with  the  permanent  cuspids  impacted  and 

malposed. 


158 


DENTAL  RADIOGRAPHY 


Fig.    138   shows   two   retained,   primary,   lower 
TI9.    13$,  central  incisors  with  no  sign  of  the  permanent  cen- 

trals.    Age  of  patient,  seventeen. 

Case — a  young  man,  age  twenty-two;    with    a 
Ti9$.  139  and  mo.       retained,  temporary,  lower,  second  molar.     The  tem- 
porary tooth  was  too  short  to  reach  its  antagonists 
in  occlusion.     For  this  reason  the  patient,  a  dental  student,   wished  to 
have  it  crowned.    Before  making  the  crown,  a  radiograph  was  taken  (Fig. 


Fig.   137.  Fig.  138. 

Fig.   137.     Two   retained   temporary  cuspids,   with   the   permanent  cuspids   impacted   and   malposed. 

(Radiograph  by  Lewis,   of  Chicago.) 

Fig.    138.      Two    retained    temporary,    lower,    central    incisors.       No    permanent    centrals    present. 

Age   of   patient,   .seventeen.      (Radiograph   by   Blum,    of    New   York    City.) 


139)  after  the  development  of  which  it  was  seen  that  the  making  of  a 
crown  was  not  indicated.  From  the  appearance  of  the  radiograph  one 
might  suppose  that  the  temporary  tooth  was  loose — its  roots  being  almost 
entirely  resorbed.     But  such  was  not  the  case. 

Fig.  140  is  a  radiograph  of  the  same  case  one  month  after  the 
extraction  of  the  temporary  molar.  Notice  how  rapidly  the  bicuspid  is 
erupting  into  its  place.  The  force  of  eruption,  which  had  been  held  in 
abeyance  for  about  eleven  years,  became  promptly  active  upon  removal 
of  the  abating  object. 

Case — young  man,  age  twenty-one.    A  retained, 
Tigs.  141  and  142.       temporary,  upper  cuspid  with  no  observable  sign  of 
the  succedaneous  cuspid.     A  radiograph  was  made 
(Fig.  141),  but,  being  a  poor  one,  it  failed  to  show  the  looked-for  tooth. 
Yet  from  the  reading  of  this  radiograph  I  was  able  to  state  with  a  mod- 
erate degree  of  certainty  that  the  cuspid  was  present  in  the  jaw.    If  the 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY     159 

tooth  itself  cannot  be  seen,  what  is  there  in  the  picture  to  lead  one  to 
believe  that  the  permanent  cuspid  is  present?  The  arrow  points  to  the 
upper  end  of  a  dark  line.  The  dark  line  represents  dense  bone  and  such 
a  line  almost  always  is  to  be  noted  in  radiographs  of  impacted  teeth. 


Fig.  139.  Fig.  140. 

Fig.  139.  Retained  temporary,  lower,  second  molar,  with  the  succedaneous  tooth  beneath  it.  Age 
of  patient,  twenty-two.  The  dark  spots  in  the  temporary  tooth  and  two  permanent  molars  are 
metal  fillings.  All  of  the  mesial  root  and  some  of  the  distal  root  of  the  temporary  tooth  resorbed. 
Fig.  140.  The  same  as  Fig.  139  one  month  after  extraction  of  the  temporary  tooth.  Observe 
how  rapidly  the  bicuspid  is  erupting.     .When  this  picture  was  made  it  could  be  seen  in  ine  mouth. 


Fig.  141.  ^^^^^^^^ 

Fig.  143. 

Fig.  141.     Age  of  patient,  twenty-one.     A  retained  temporary  upper  cuspid.      The  arrow  points  to 
a   dark   line   following  along  the   side   of   the   impacted  cuspid.      The   impacted   tooth   itself   cannot 

be   seen. 
Fig.  142.     The  same  as  Fig.  141,  but  taken  at  a  diiferent  angle  and  showing  the  permanent  cuspid. 

To  verify  or  disprove  my  deductions  another  radiograph  was  made 
(Fig.   142),  which  shows  the  impacted  cuspid  clearly. 

The  question  arises  naturally,  What  operative  procedure  should  be 


i6o  DENTAL  RADIOGRAPHY 

resorted  to  in  such  cases  as  the  one  just  described?  Had  the  patient 
been  younger,  or  had  the  root  of  the  temporary  cuspid  been  much  resorbed, 
or  had  the  pressure  of  the  impacted  tooth  been  causing  resorption  of 
the  permanent  lateral  root,  or  central  root,  or  had  the  patient  been  suf- 
fering from  neuralgia,  periodic  headaches,  or  any  nervous  disorder — 
had  any  of  these  conditions  existed  the  temporary  tooth  should  have  been 
extracted  immediately,  space  made  in  the  arch  for  the  permanent  tooth 
and  such  orthodontic  assistance  given  as  might  prove  necessary  to  cause 
it  (the  permanent  cuspid)  to  erupt  into  its  proper  place.     As  none  of 


Fig.  143.  The  roots  of  a  lower,  first,  permanent  molar  not  quite  fully  formed.  Age  of  patient, 
eiglit    years   and   four   months.      Only   the    crowns    of   the   second    bicuspid   and    second    molar    are 

formed. 

these  conditions  did  exist,  and  as  the  patient  expressed  a  definite  disin- 
clination to  have  anything  done  unless  absolutely  and  imperatively  neces- 
sary, the  case  was  dismissed  with  the  understanding  that  the  condition 
should  be  kept  under  rigid  observation.  The  man  may  go  through  life 
without  trouble,  or  inside  of  a  year  he  may  be  suffering  almost  any 
nervous  disorder  from  simple  neuralgia  to  insanity* ;  or  he  may  lose 
the  temporary  cuspid  as  a  result  of  the  resorption  of  its  roots,  or  he 
may  even  lose  the  lateral  or  central  as  a  result  of  absorption  of  their 
roots,  or  suppuration  may  occur. 

3.    to  Cearn  if  tb(  Roots  of  Children's  teetb  arc  Tully  Tormcd. 

Case — patient,  eight  years  and  four  months  old. 
Tl|.  143.  A  large  cavity  in  a  lower  first,  permanent  molar. 

To  remove  absolutely  all  of  the  decalcified  dentin 
meant  extensive  exposure  of  the  pulp,  and,  therefore,  pulp  devitaliza- 
tion, extirpation  and  canal  filling.  But  should  we  practice  pulp  devitali- 
zation in  such  a  case  ?     If  the  roots  of  the  tooth  are  fully  formed,  yes ; 

*Dr.  Upson. 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY     i6t 

if  the  roots  are  not  fully  formed,  no.  A  radiograph  (Fig.  143)  was 
made  and  shows  that  the  roots  of  the  tooth  are  not  quite  fully  formed. 
Accordingly  exposure  of  the  pulp  was  avoided,  the  unremoved,  decalcified 
dentin  painted  with  silver  nitrate,  a  paste  of  zinc  oxide  and  oil  of  cloves 
placed  in  the  bottom  of  the  cavity  and  the  tooth  filled  with  cement,  the 
object  of  this  treatment  being  to  conserve  the  pulp  in  the  tooth  at  least 
until  the  roots  are  fully  formed. 

Often  a  child  meets  with  some  accident  which  breaks  off  the  angle 
of  a  central  or  lateral  incisor.     To  restore  the  angle  sometimes  necessi- 


Fig    144.      Post-collar   crown   on   a  temporary  cuspid   root.      The   permanent   cuspid   erupted   down 

to  the   post  of  the  crown.      The  dark   shadows  in  the  region   of   the   temporary   cuspid   crown   are 

numbers  used  to  mark  the  negative.      (Radiograph   by  Kells,  of  New   Orleans.) 

tates  the  removal  of  the  pulp  and  the  placing  of  a  post  in  the  canal.  The 
question  should  always  be  raised,  "is  the  tooth's  root  fully  formed?" 
If  it  is,  we  may  proceed  with  the  devitaHzation,  but  if  not,  some  tem- 
porary restoration  should  be  made  and  the  pulp  conserved  until  it  has 
fulfilled  its  function  of  root  development.  Whether  the  root  is  fully 
formed  or  not  can  be  determined  only  by  the  use  of  the  X-rays. 

In  a  child's  mouth  we  occasionally  find  an  anterior  tooth  so  badly 
decayed  that  crowning  is  indicated.  Again  we  are  confronted  with  the 
question,  "is  the  root  fully  formed?"  And  whether  we  should  devitalize 
and  crown  the  tooth  or  keep  it  patched  with  cement  for  a  year  or  so 
depends  entirely  upon  the  answer  which  the  radiograph  may  make  to 
this  question. 

4.    to  Determine  lUbetber  a  tooth  be  One  of  the  Primary  or  Secondary  Set. 

What  treatment  we  give  a  tooth  depends  very  largely  on  whether 
it  be  of  the  permanent  or  deciduous  set.  If  a  man  knows  his  dental 
anatomy  as  well  as  he  should  it  is  usually  easy  for  him  to  determine 
whether  a  tooth  be  a  primary  or  secondary  one.  Occasionally,  how- 
ever, we  find  a  tooth   (usually  an  upper  lateral  incisor)    that  looks  as 


i62  DENTAL  RADIOGRAPHY 

much  like  a  member  of  one  set  as  the  other  and  the  radiograph  must  be 
used  to  arrive  at  a  definite  conclusion.  To  mistake  a  permanent  tooth 
for  a  deciduous  one  and  extract  it  (Fig,  130)  is  an  inexcusable  and  dis- 
astrous blunder. 

Sometimes  a  tooth  is  so  badly  decayed  (the  crown  may  be  entirely 
destroyed)  that  it  is  impossible  to  determine  by  simple  ocular  observa- 
tion whether  it  be  a  temporary  or  a  permanent  one.  The  radiograph  can 
be  used  to  great  advantage  in  such  cases.  If  the  carious  tooth  be  one 
of  the  temporary  set,  with  the  succedaneous  tooth  ready  to  take  its  place, 
it  should  be  extracted.  If  the  carious  tooth  be  a  permanent  one,  the 
radiograph  shows  the  size  and  condition  of  its  roots. 

Case — a  post-collar  cuspid  crown  became  loose. 
Tig.   144,  A  radiograph   (Fig.  144)  was  made  and  shows  that 

the  crown  is  placed  on  a  temporary  cuspid  root.  Part 
of  the  root  of  the  temporary  tooth  is  resorbed  and  the  permanent  cuspid 
has  erupted  down  to  the  end  of  the  post  of  the  crown.  The  very  dark 
shadows  in  the  region  of  the  temporary  cuspid  crown  are  caused  by  lead 
numbers  placed  against  the  film  packet  to  mark  the  negative. 

5.    Co  Determine  (Uben  to  Extract  temporary  teetb. 

The  best  rule  ever  formulated  for  the  extrac- 
Tlg.  145.  tion  of  deciduous  teeth  reads,  "Extract  a  deciduous 

tooth  only  when  its  successor  is  ready  to  take  its 
place."  There  are  many  cases  where  the  operator  is  able  to  detect  the 
presence  of  the  succedaneous  teeth  by  ocular  and  digital  examination. 
In  about  as  many  cases,  however,  the  only  way  to  determine  the  presence 
of  such  teeth  is  by  the  use  of  the  radiograph.  Thus  the  rule  just  quoted 
is  one  which,  when  followed,  necessitates  the  use  of  the  radiograph.  Fig. 
145  is  of  a  case  where  extraction  of  the  temporary  first  molar  is  indicated, 
and  extraction  of  the  temporary  second  molar  is  contraindicated.  The 
temporary  second  molar  should  not  be  removed  for  a  year  or  so — not 
until  the  second  bicuspid  is  just  ready  to  take  its  place. 

Often  in  practice  we  are  confronted  with  abscessed  temporary  teeth. 
The  age  of  the  patient  is  such  that  we  cannot  decide  whether  the  tieeth 
are  loose  as  a  result  of  the  abscessed  condition,  or  because  of  resorption 
of  the  roots  and  the  presence  of  the  succedaneous  teeth.  A  radiograph 
of  the  case  will  enable  us  to  decide,  and  our  treatment  will  be  governed 
accordingly.  Not  only  will  the  radiograph  show  the  operator  when  de- 
ciduous teeth  should  be  removed,  but  will  aid  him  in  their  removal — 
especially  in  cases  where  the  temporary  teeth  are  badly  decayed — by 
showing  the  exact  size  and  location  of  the  temporary  teeth's  roots  and 
the  position  of  the  succedaneous  teeth. 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY     163 

6.    to  Sbow  m  Ortboaontist  Ulbcn  f,z  may  move  tbc  eoming  Permanent  Ceetb  by 
mooing  tbe  Deciduous  teetb. 

It  impressed  me  very  much  when  I  first  heard  of  radiographically 
observing,  and  then  regulating,  teeth  before  their  eruption.  I  heard  of 
this  in  a  lecture  by  Dr.  Ottolengui.     I  quote  Dr.  Ottolengui : 

"One  of  the  difficult  operations  which  confronts 

Tig.  146.  the  orthodontist  at  times  is  the  bodily  movement  of 

the  bicuspids  buccally.     Very  often  in  the  past  at- 


Fig.    145.      This    picture    shows    that    the    temporary    first    molar    may    be    extracted.      The    tem- 
porary  second   molar   should   not   be   extracted    for   a   year   or   so,    when   the   second    bicuspid    will 
be   just   ready   to   take   its   place.      (Radiograph    by   Lewis,    of   Chicago.) 


tempts  to  widen  the  arch,  after  the  eruption  of  the  bicuspids,  has  resulted 
in  tipping  the  crowns  buccally,  the  apices  of  roots  remaining  in  the  orig- 
inal apical  arch.  Hence,  one  of  the  chief  advantages  of  early  orthodontic 
interference  lies  in  the  fact  that  the  temporary  molars  may  be  moved 
buccally,  carrying  with  them  the  underlying  bicuspids,  and  this  advantage 
is  made  more  clear  if  it  be  recalled  that  at  this  period  the  bicuspid  roots 
are  but  partly  formed.  Even  when  the  roots  of  the  temporary  molars 
are  already  considerably  absorbed,  still  enough  may  be  left  to  serve  to 
deflect  the  oncoming  bicuspids  in  the  direction  desired. 

"This  slide  (Fig.  146),  from  the  collection  of  Dr.  Matthew  Cryer 
(radiograph  by  Pancoast,  of  Philadelphia),  shov/s  nicely  the  usual  rela- 
tion of  the  erupting  bicuspids  to  their  predecessors,  the  temporary  molars. 
It  will  be  noted  that  the  apices  of  the  bicuspids  are  still  unformed,  and  it 
is  clear  that  if  these  teeth  can  be  led  into  proper  positions  during  eruption, 
the  formation  of  the  apices  afterward  afifords  the  most  permanent  'reten- 
tion.' A  casual  glance  at  the  upper  temporary  molars  might  create  a 
doubt  as  to  the  probability  of  moving  the  unerupted  bicuspids,  but  there 
is  an  easily  overlooked  factor,  viz.,  the  palatal  roots  of  these  molars  do 


164 


DENTAL   RADIOGRAPHY 


not  show  in  radiographs  of  this  region  at  this  period,  because  they  lie  be- 
hind the  crowns  of  the  bicuspids ;  that  is  to  say  'behind,'  in  relation  to 
the  source  of  light,  the  X-ray  tube." 


Fig.    1-16.      Radiograph   made   to   show   relation    of  temporary  molar   roots   to   advancing   bicuspids. 
(Collection  of  Dr.  Cryer.     Radiograph  by  Pancoast,  of  Philadelphia.) 


7.    to  Observe  mopIng  teeth. 

Fig.  147  demonstrates  the  congenital  absence  of 

Tigs.  147,  14$  and  149.    the  upper  lateral  incisors.   The  orthodontic  appliance, 

seen  in  the  radiograph,   is  being  used  to  draw   the 

centrals  together.     It  was  highly  important  in  this  case  that  the  teeth  be 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY     165 

moved  through  the  alveolar  process  en  masse,  and  not  tipped.  The 
movement  desired  was  one  which  would  make  the  roots  parallel  when 
the  crowns  of  the  teeth  came  together,  so  that  posts  could  be  set  in  the 
canals  of  the  central  incisors,  and  a  bridge  made  to  restore  the  lost  lat- 
erals. Fig.  148  was  taken  about  a  month  after  Fig.  147.  It  shows  that 
the  teeth  have  been  moved  together,  but  there  is  too  much  tipping  of  the 


Fig.    147.  Fig.    148.  Fig.   149. 

Fig.  14  7.     Congenital  absence  of  upper  lateral  incisors.     The   orthodontic  appliance   seen  is   being 

used   to    draw   the    central   incisors   together. 
Fig.   148.      This  radiograph   was   made   one  month  after   Fig.   147.      It  will  be   seen   that   there  has 

been   considerable   movement   of   the  teeth.     The  left   central   is   tipped    considerably. 
Fig.    149.      Made   one   month    after   Fig.    148.      The    central    incisors    are   together    and    their    roots 

almost  parallel. 


left  incisor — not  enough  movement  of  the  tooth  at  the  apex  of  the  root, 
compared  to  the  movement  of  the  crown.  It,  therefore,  became  necessary 
to  modify  the  force  which  was  being  used.  This  was  done,  and  Fig.  149 
shows  the  teeth  together  and  the  roots  almost  parallel. 

A  case  in  the  practice  of  Dr.  C.  Edmund  Kells, 
Tigs.  150,  151  and  152.  Jr.,  and  reported  by  him  in  the  May  number  of 
Items  of  Interest,  191  i.  Fig.  150  shows  a  mal- 
posed  permanent  cuspid  above  the  temporary  cuspid,  the  root  of  which 
is  somewhat  resorbed.  Age  of  patient,  eleven  years.  Fig.  151  was 
made  one  year  and  seven  months  after  Fig.  150.  "Compare  this  pic- 
ture with  Fig.  150,  and  it  will  be  seen  that  the  permanent  cuspid  has 
migrated  in  a  line  with  its  long  axis,"  causing  resorption  of  the  perma- 
nent lateral  root.  The  temporary  cuspid  was  extracted,  but  the  perma- 
nent tooth  did  not  erupt  into  its  position  in  the  arch.  It  was,  therefore, 
concluded  that  the  tooth  "would  have  to  be  brought  down  by  some 
mechanical  means."  Accordingly,  the  gum  tissue  and  overlying  process 
were  "slit  down  to  the  cuspid  and  then  gently  spread  apart,  and  the 


i66 


DENTAL   RADIOGRAPHY 


cuspid  was  exposed  to  view.  A  piece  of  iridio-platinnm  wire  was 
then  shaped,  as  shown  in  Fig.  152,  and  the  hook  was  worked  supposedly 
under  the  mesial  prominence  of  the  cuspid,  and  a  rubber  ring  attached 
to  the  loop  on  the  other  end,  and  secured  to  a  lug  on  the  molar  band,  all 
as  shown  in  Fig.  152,  which  is  a  skiagraph  of  the  case  with  the  appliance 


Fig.  150.  Fig.    151. 

Fig.    150.       Malposed,    permanent    cuspid    above    the    temporary    cuspid,     tlie    root    of    the    latter 

somewhat   resorbcJ. 

Fig.   151.      Same    as   Fig.    150    one   year   and    seven   months    later.      Observe    that    the    cuspid    has 

migrated  in  the   line   of  its  long  axis.      The  permanent   lateral  root  is  badly    resorbed. 


Fig.   152.     Same  as  Figs.  150  and  151  after   removal  of  the  temporary  cuspid.     The   wire  hooked 

over    the    cusp    of    the    tooth    was    thought    to    be    placed    over    the    mesial    prominence    until    the 

radiograph   was  made.      (See   Fig.   459.) 


in  position.  Imagine  my  surprise  to  find  by  this  picture  that  the  hook 
was  not  anywhere  near  where  I  had  thought  I  put  it.  Instead  of  being 
well  up  under  the  mesial  prominence,  it  was  merely  caught  under  the 
point  of  the  tooth,  and,  of  course,  it  slipped  off  shortly  after  the  patient 
left  the  office.  Upon  her  return  a  hook  ^g  of  an  inch  longer  was  fitted 
in  place,  and  this  time,  with  a  radiograph  as  a  guide,  there  was  no  mis- 
take about  its  placement.     The  appliance  was  worn  for  several  weeks,  at 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY     167 


the  end  of  which  time  the  point  of  the  cuspid  having  been  brought  to  the 
surface  of  the  gum,  it  was  removed  and  the  tooth  allowed  to  erupt  by  its 
own  volition.  Despite  the  great  destruction  of  its  root  the  lateral  re- 
mains firm  and  apparently  healthy." 


$.   Tn  €ase$  of  Supernumerary  teeth. 

A  case  in  the  practice  of  Dr.  B.  S 
Chicago.      Patient's    age,    twelve   years. 


Partridge, 

Tig.  153.  Chicago.      Patient's    age,    twelve   years.      The    teeth 

wert'  being  regulated,  and  the  radiograph,  Fig.  153, 


Fig.   153.  Fig.  154. 

Fig.    153.      A    and    B,    supernumerary    tooth    bodies.      C,    the    crown    of    the    temporary    cuspid. 

D,   the   permanent  cuspid.      (Radiograph   by    Lewis,   of   Chicago.) 

Fig.   154.     A  .and   B  are  supernumerary  teeth.      (Radiograph  by   Lewis,   of  Chicago.) 


was  taken  to  determine  the  presence  or  absence  of  the  permanent  lower 
cuspid.  A  httle  supernumerary  tooth  (A)  could  be  seen  in  the  mouth 
occupying  a  part  of  the  space  which  should  have  been  occupied  by  the 
permanent  cuspid.  The  two  shadows  marked  "B"  are  two  more  super- 
numerary tooth  bodies.  The  larger  shadow  marked  "C"  is  the  crown  of 
the  temporary  cuspid,  which  had  never  erupted.  The  large  shadow  to 
the  left,  marked  "D,"  is  the  permanent  cuspid  pressing  against  the  side 
of  the  lateral  at  the  apex  of  its  root.  The  three  supernumerary  bodies 
and  the  crown  of  the  temporary  cuspid  (the  root  was  resorbed)  were 
removed,  allowing  the  permanent  cuspid  to  erupt. 

Just  lingually  to  each  central  incisor  is  a  super- 
fig.  154.  numerary   tooth.      One    (A)    could   be   seen   in   the 
mouth,    but   there    was    no    evidence    of    the   other. 
Neither  central  nor  lateral  incisor  roots  are  as  yet  fully  formed,  and  the 


i68 


DENTAL  RADIOGRAPHY 


laterals  have  not  yet  erupted.  Indeed,  before  the  picture  was  made,  it 
seemed  that  a  peg-shaped  lateral  was  erupting  just  lingually  to  the  cen- 
tral.    The  radiograph  shows  this  tooth  to  be  supernumerary. 

Dr.  T.  W.  Brophy,  of  Chicago,  reports  a  case  of  insistent  suppura- 
tion due  to  an  impacted  supernumerary  tooth,  which  was  found  by  the 
use  of  the  radiograph.  Dr.  Brophy  calls  attention  to  the  fact  that  a  cor- 
rect and  definite  diagnosis  could  not  have  been  made  by  any  means  at  our 
command  except  the  X-rays.  The  case  recovered  promptly  upon  removal 
of  the  supernumerary  tooth.  I  regret  that  I  have  been  unable  to  obtain 
radiographs  of  this  case. 

fig.  (55.  An  impacted  upper  fourth  molar. 


Fig.    155.  Fig.   156. 

Fig.    155.     An   impacted  upper   fourth  molar. 
Fig.  156.     A  supernumerary  tooth  in  the  canal  of  a  cuspid  tooth.      (Radiograph  by  Clarence  Van 

Woert,   of   New   York   City.) 

To  me  this  is  a  most  remarkable  case — a  super- 
Tig.  156.  numerary  tooth  in  the  canal  of  a  cuspid  tooth — a 
tooth  inside  of  a  tooth.  The  supernumerary  tooth 
has  a  root  canal,  and  the  crown  is  covered  with  enamel.  There  is  no 
doubt  of  the  fact  stated,  because  Dr.  Van  Woert,  after  radiographing  the 
case,  drilled  into  the  permanent  cuspid  and  found  the  enamel-covered 
supernumerary  within.  The  radiograph  is  not  as  good  as  I  wish  it  were. 
The  upper  two-thirds  of  the  roots  of  the  teeth  shows  fairly  well  but  there 
is  a  confusion  of  shadows  in  the  lower  third  and  m  the  crown. 

9.   Tn  0a$c$  of  Tmpacted  teeth  as  an  Hid  in  extraction. 

Impacted,    lower,    third    molar    tipped    to    the 
Tig.  157.  mesial.    The  picture  shows  that  in  this  case  a  knife- 

edge  stone  in  the  dental  engine  could  be  used  to  ad- 
vantage, cutting  away  the  mesio-occlusal  portion  of  the  third  molar,  and 


THE   USES  OF  THE  RADIOGRAPH  IN  DENTISTRY     169 

so  greatly  facilitating  the  removal  of  the  tooth.  Observe  the  absorption 
of  the  distal  surface  of  the  second  molar  (the  light  area),  due  to  pressure 
against  it;  and  the  large  abscessed  cavity  (light  area)  between  the  sec- 
ond and  third  molars,  extending  down  to  the  apex  of  the  second  molar. 
This  radiograph  is  of  particular  interest,  because  it  shows  so  clearly  an 
abscess  caused  by  impaction. 

That   the   pressure   of   an   impacted   tooth  may 

Tigs.  15$  and  159.       ^^^^^^    absorption    of    the    tooth    against    which    the 

pressure  is  brought  to  bear,  is  further  illustrated  in  Figs.  158  and  159. 


Fig.    157.  Fig.   158. 

Fig.  157.  An  impacted  lower  third  molar.  The  light  area  between  the  second  and  third  molars 
represents  a  destruction  of  bony  tissue,  arrow  A.  Arrow  B  points  to  a  light  area,  which  rep- 
resents the  absorption  of  the  second  molar.      (Radiograph  by  Blum,   of  New  York  City.) 

Fig.  158.  An  impacted  upper  third  molar.  The  arrow  points  to  a  light  area  representing  absorp- 
tion of  the  upper  second  molar.  Notice  the  very  poor  filling  in  the  first  molar;  it  fills  the 
interproximal  space  between  the  first  and  second  molars.     (Radiograph  by  Ream,  of  Chicago.) 

In  Fig.  158  the  arrow  points  to  a  light  area  representing  absorption 
of  the  upper  second  molar,  due  to  the  pressure  of  the  third  molar  against 
it.  A  study  of  this  radiograph  gives  the  dental  surgeon  a  good  idea  of 
how  he  should  apply  his  force  in  extraction. 

Fig.  159  is  a  case  of  Dr.  Cryer's.  I  quote  Dr.  Cryer:  Fig.  159 
"shows  an  impacted,  lower,  third  molar  resting  against  the  posterior  root 
of  the  second  molar.  It  will  be  seen  that  the  root  of  the  second  molar  is 
much  absorbed,  which  caused  considerable  trouble.  Removal  of  the  sec- 
ond molar  gave  relief  to  the  patient.  .  .  .  The  upper  third  molar  is 
in  an  awkward  position." 

Figs.   160  and   161    show  impacted  upper  third 
Tigs.  160  and  161.        molars.     The  unerupted  teeth  lie  in  the  jaws  at  en- 
tirely different  angles.    The  value  of  such  knowledge 
to  the  operator,  about  to  extract,  is  apparent. 

This  radiograph   (Fig.   162)   shows  the  surgeon 

Tig.  162.  just  how  much  bone  must  be  dissected  away  before 

the  malposed  tooth  can  be  removed.    Patients  seldom 


I70  DENTAL   RADIOGRAPHY 

know  that  the  removal  of  a  tooth  is  not  always  a  simple  operation.  They 
are  therefore  inclined  to  blame  the  operator  if  the  tooth  is  not  quickly 
removed,  instead  of  crediting  him  with  working  dexterously  on  a  difficult 
operation.     They  are  likewise  unwilling  to  pay  a  fee  in  proportion  to  the 


Fig.    159.      Impacted   upper   and   lower   third   molar.      Absorption   of   the    distal   root   of   the    lower 
second  molar.      (Radiograph   by   Pancoast,   of   Philadelphia.") 

difficulty  of  the  operation,  as  compared  to  other  operations.  The  removal 
of  the  third  molar,  shown  in  Fig.  162,  is  a  more  difficult  operation  than  the 
removal  of  a  vermiform  appendix.  By  showing  patients  radiographs  of 
such  cases  the  dentist  will  gain  their  earnest,  intelligent  co-operation. 
They  will  know  just  what  is  done  for  them,  and  for  the  first  time  in  their 


THE   USES  OF  THE  RADIOGRAPH  IN  DENTISTRY     171 

lives  they  will  understand  that  the  extraction  of  a  tooth  may  be  a  serious, 
difficult  and  expensive  operation. 

The  following  report  of  this  case  is  by  Dr.  F.  K. 

Tifl.  163*  Ream,  of  Chicago.   "Patient's  age,  seventy-two  years. 

Symptoms :    Swelling  near  symphysis  thought  to-  be 

the  result  of  wearing  an  artificial  denture.    Considerable  pain.    Diagnosed 


Fig-   160.  Fig.   161. 

Fig.  IGO.     Impacted  upper  third  molar. 
Fig.   161.      Impacted   upper   third   molar.      Notice   the    difference    in   the    position    of   the   impacted 
tooth  shown  in  this  case  and  in  Fig.   160. 


Fig.  162.  Fig.   163. 

Fig.  163.  Impacted  lower  third  molar  with  its  occlusal  surface  presenting  mesially.  The 
radiograph  shows  the  dental  surgeon  how  much  bone  must  be  burred  or  chiseled  away  before  the 

tooth  cnn  be  removed.      (Radiop^rpoh  by  Ream,   of  Chicago.) 

Fig.    163.      Impacted    bicuspid    in    an    otherwise    edentulous    mouth.      Age    of    patient,    72    years. 

(Radiograph  by  Ream,   of  Chicago.) 

cancerous  by  surgeons,  and  patient  advised  to  go  to  the  hospital  for  opera- 
tion. The  radiograph  (Fig.  163)  shows  an  impacted  bicuspid  in  the 
otherwise  edentulous  jaw.  Operation:  Alveolar  process  burred  away 
and  tooth  removed.     Result:    Immediate  and  complete  recovery." 


1^2 


DENTAL  RADIOGRAPHY 


Fig.  164  is  a  case  of  Dr.  Cryer's.     I  quote  Dr. 
Tig.  164.  Cryer:    Fig.  164  "shows  a  lower  third  molar  passing 

under  the  second  molar  and  becoming  lodged  be- 
tween the  first  and  second  molar,  the  crown  of  the  third  molar  pushing 
against  the  root  of  the  first  molar.  The  first  molar  was  extracted,  which 
cleared  up  the  neuralgia,  and  the  third  molar  pushed  up  into  the  place 
of  the  first  molar." 


Fig.    164. 


Lower    third    molar    lodged    between    the    first    and    second    molars. 
Pancoast,  of  Philadelphia.) 


(Radiograph    by 


Fig.    165   is  also  a  case  of  Dr.   Cryer's.     The 
Tig.  165.  radiograph   shows    an   impacted   upper   third   molar, 

with  the  occlusal  surface  presenting  upwards.  Dr. 
Cryer's  remarks  concerning  this  case  are  interesting.  I  quote  Dr.  Cryer : 
Fig.  165  "shows  the  occluding  surface  of  the  upper  third  molar  pointing 
upward  towards  the  posterior  portion  of  the  orbit.  The  patient  had 
been  suffering  from  disturbance  of  the  eye  for  a  long  time.  Considerable 
improvement  took  place  in  the  eye  soon  after  extraction  of  the  inverted 
tooth." 

10.    Co  Determine  the  number  of  Canals  In  Some  teetb. 
It  will  be  noticed  that  I  say  "to  determine  the  number  of  canals  in 
some  teeth."     Of  course,  it  is  not  necessary  to  use  the  radiograph  each 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY     173 

time  we  open  into  a  tooth  to  learn  how  many  canals  that  tooth  may  have. 
But  occasionally  I  do  find  it  necessary  or  expedient  to  use  the  radiograph 
to  verify  or  disprove  the  existence  of  some  unusual  condition  suspected. 


Fig.   165.      Impacted   upper   third  molar  with   the   occlusal   surface   pointing   upward.      (Radiograph 

by   Pancoast,   of   Philadelphia.) 

Case :    An  upper  first  (  ?)  molar  in  which  but  one 
•yig.  166.  small  canal  could  be  found.    After  searching  for  the 

other  two  canals  for  a  few  minutes,  the  one  canal 
was  filled  with  gutta-percha,  and  a  radiograph  made  (Fig.  166)  ;  this 
shows  that  the  tooth  has  but  one  canal.  In  this  case  the  radiograph  saved 
considerable  work  and  worry  on  the  part  of  the  operator.  The  tooth  is 
probably  a  second  molar  moved  forward  in  the  place  of  an  extracted 
first  molar,  judging  from  the  manner  in  which  it  is  tipped  and  from  the 
fact  that  it  has  only  one  canal. 

This  case  was  in  the  hands  of  one  of  the  most 

TIfl.  167.  expert   operators    in    Indianapolis.      The   lower   first 

bicuspid  had  been  devitalized,  and  the  pulp  removed. 


1/4 


DENTAL  RADIOGRAPHY 


but  the  tooth  remained  sore.  Radiography  was  resorted  to  to  learn,  if 
possible,  the  cause  of  the  persistent  pericementitis.  A  piece  of  ligature 
wire,  such  as  is  used  by  orthodontists,  was  placed  in  the  canal  and  radio- 
graph Fig.  167  made.  The  wire  follows  the  enlarged  canal.  But  this 
particular  tooth  happens  to  have  two  canals.  The  unopened  canal  is  seen 
to  the  distal  of  the  wire.  If  a  man,  having  the  skill  of  the  operator  who 
handled  this  case,  misses  a  canal,  as  this  man  did,  then  I  firmly  believe 
that  the  mistake  is  one  that  any  man,  however  skillful,  is  liable  to  make. 


Fig,  166. 


Fig.  167. 


Fi?.  166.     Upper  first  (?)  molar  with  but  one  canal  which  is  filled. 

Fig.    167.      The   dark   streak  in   the   first  bicuspid   is   a   wire   passing   into   the    canal.      This   tooth 

has   another  canal,   which  can  be   seen   as  a  light  streak   distally   to   the   wire.      The  more   or   less 

oval   dark    spot   at  the  neck   of  the   first  bicuspid   is   a  buccal   cervical   filling.      The   cavity    in    the 

crown  of  the  tooth  is  stopped  up  with  gutta-percha. 


Let  me  say  here  that  a  lower  bicuspid,  or  cuspid  with  two  canals,  is 
not  such  an  unusual  occurrence,  as  it  is  generally  believed  to  be.  Men 
have  shown  me  such  teeth,  and  spoken  of  them  as  though  they  were  rare 
anomalies.  As  a  teacher  of  operative  technic,  I  devote  a  part  of  my  time 
to  the  dissection  of  teeth.  In  this  work  I  handle  thousands  of  disasso- 
ciated human  teeth.  In  my  work  of  last  year,  for  example,  I  estimate 
that  I  observed  six  to  eight  thousand  teeth.  And  among  these  I  noticed 
not  less  than  seven  lower  cuspids  and  five  lower  bicuspids  with  two 
canals  each. 

Without  printing  the  radiograph,  which  is  not  a  very  good  one,  I 
quote  the  legend  which  appears  beneath  it  in  the  last  edition  of  Buckley's 
"Modern  Dental  Materia  Medica,  Pharmacology  and  Therapeutics."  "In 
this  case  the  author  desires  to  insert  a  bridge.  On  opening  into  the  third 
molar  and  second  bicuspid,  which  teeth  were  to  be  used  for  the  abut- 
ments, we  were  unable  to  find  any  canals  in  the  bicuspid,  and  only  a  small 
canal  in  the  molar.    The  skiagraph  confirms  the  clinical  findings." 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY     175 

IK    m  an  Jlia  in  Tilling  the  €anal$  of  teetb  witb  Carac  Jlpica)  Toramina. 

To   demonstrate   this   use   of   the   radiograph   a 
Tig.  16$.  central    incisor    with    a    large    apical    foramen    was 

chosen,  and  an  orthodontic  ligature  wire  passed  into 
the  canal  until  the  patient  received  sensation.  The  worthlessness  of  the 
"sensation  test,"  as  a  guide  in  filling  to  the  apex  of  canals  is  demonstrated 
by  Fig.  168,  which  shows  the  wire  penetrating  the  tissues  four  or  fi^^e 
millimeters  beyond  the  apex  of  the  tooth.  After  the  radiograph  (Fig. 
168)  was  made,  the  wire  was  removed,  and  that  part  of  it  penetrating  the 
apex  cut  off,  or  as  nearly  as  could  be  judged  from  the  appearance  of  the 
radiograph. 


Fig.   168.  Fig.   169.  Fig.   170. 

Fig.   168.     A  wire  passing  through  a  large  apical  foramen  in  an  upper,   centra!    incisor,  extending 
several  millimeters  into  the  tissues  above  the  apex  of  the  root. 

Fig.    169.      The    same"  case   as   Fig.   168,    after   the   wire   has  been    removed,    a   part    of   it    cut   off 
and  reinserted  into  the  canal.     The  wire  reaches  just  to  the  apical   foramen. 

Fig.  170.  The  same  case  as  Figs.  168  and  169,  showing  a  canal  filling  of  gutta-percha  closing 
the  apical  foramen,  not  penetratir.g  through  it,  and  not  leaving  a  little  ot  the  canal  unfilled 
at  the   apex  of  the  root.      The  entire  canal  is  not  filled,  because  there   is  to   be   a  post  set   in  it. 

Next  the  shortened  wire  was  reinserted  and  an- 

Tifl.  169.  other  radiograph  (Fig.  169)  made.     This  shows  that 

my  judgment  in  cutting  off  the  wire  in  this  particular 

case  was  unusually  good.    The  wire  reaches  just  to  the  apex.     It  may  be 

necessary  to  make  two  or  three  trials  before  the  wire  is  placed  just  to 

the  apex. 

With  the  length  of  the  wire  as  a  guide  to  the 
Tifl.  170.  length  of  the  root,  the  proper  distance  was  measured 

on  a  canal  plugger,  and  the  distance  marked  on  the 
plugger  by  passing  it  through  a  little  piece  of  base-plate  gutta-percha, 
stopping  the  gutta-percha  on  the  plugger  at  a  distance  from  its  end  equiv- 
alent to  the  length  of  the  wire.     The  end  of  the  canal  plugger  was  then 


176 


DENTAL  RADIOGRAPHY 


warmed  slightly,  and  brought  in  contact  with  a  small  piece  of  gutta- 
percha canal  point.  With  the  piece  of  gutta-percha  so  fastened  on  the 
canal  plugger,  it  was  carried  into  the  canal  a  sufficient  distance  to  reach, 
but  not  pass,  beyond  the  apex.  (Fig.  170.)  A  slight  twist  of  the  plugger 
will  disengage  it  from  the  gutta-percha,  when  the  latter  may  be  tamped 
firmly,  but  not  too  forcibly,  to  place.  No  further  filling  of  the  canal  was 
done  in  this  case,  the  canal  being  left  open  to  receive  a  post. 

What  will  happen  if  the  canal  filling  either  fails  to  reach  the  apex  or 
passes  a  little  beyond  it  ?  An  abscess  may  result.  If  the  canal  filling  fails  to 
reach  the  apical  foramen,  in  such  cases  as  the  one  just  described,  an  abscess 
is  very  Hkely  to  occur.     If  perfectly  aseptic  gutta-percha  is  used  as  a 


Fig.  171 


Fig.  172 


Fig.  171.     The  dark  streaks  in  the  lower  molar  are  wires  in  the  canals.      (Operator,  Dr.  Moag, 
Indianapolis.)      Fig.   172.      The  same  as  Fig.    171   after  canal  filling. 


canal  filling,  and  the  tissues  above  the  apex  are  not  infected,  then  the 
passage  of  a  little  gutta-percha  into  the  apical  tissues  will  probably  not 
result  in  suppuration  or  even  inflammation,  so  well  do  tissues  tolerate 
gutta-percha.  But  the  fact  remains :  The  ideal  canal  filling  is  one  which 
fills  the  canals,  neither  falling  short  of  the  end  of  the  root  nor  passing 
beyond  it.     (For  further  consideration  see  Appendix  Chap.  XI.) 


12.    to  Cearn  if  0anal$  Jlrc  Ooen  and  enlarged  to  tbe  Bptx  Before  Tilling,  and  to 
Observe  the  0ana1  Tilling  JIfter  the  Operation. 

A  radiograph  of  the  tooth  before  attempting  to  open  its  canals  will 
often  be  found  of  great  value  to  the  operator.  This  is  particularly  true 
in  cases  where  the  shape  or  size  of  the  roots  is  unusual. 

At  any  time  during  the  process  of  opening  canals  the  operator  may 
insert  wires  and  make  a  radiograph  to  see  how  far  he  has  penetrated. 


THE   USES   OF   THE  RADIOGRAPH  IN  DENTISTRY    i^j 

Fig.  1 71  is  the  first  radiograph  made  of  the  particular  case  it  ihustrates, 
and  shows  the  wires  (in  this  case  old  broaches)  reaching  the  ends  of  the 
canals. 

A  wire  Avith  a  flat  end  does  not  enter  canals  readily.  Engage  the 
wire — orthodontia  ligature  wire  for  example — in  the  broach  holder,  for 
the  dental  engine  suggested  by  Dr.  Gallic,  hold  the  end  of  the  wire 
with  emery  cloth  between  the  thumb  and  finger,  and  revolve  the  engine. 
In  this  way  the  wire  may  be  pointed  and  reduced  to  any  desired  size. 

It  is  not  always  a  physical  possibility  to  reach  the  ends  of  the  canals 
in  molar  teeth.  It  is  very  often  necessary  to  devote  from  five  to  ten 
hours  on  a  molar  to  open  its  canals  to  the  end. 


Fig.    173.      Canals   in   an   upper   first    molar   well   filled.      (Operator,    Dr.    Emmert,   Indianapolis.) 

Fig.    174.      Wire   passing   to   the   mesial   through   a  perforation   in   the    mesial    side    of    the   mesio- 
buccal  root  of  an  upper  first  molar. 


Even  after  the  canals  are  open  to  the  end,  the  fact  having  been 
demonstrated  with  diagnostic  wires  and  radiographs,  it  is  not  at  all  un- 
common for  the  operator  to  fail  to  fill  the  canals  the  first  time  he  tries. 

Dr.  M.  L.  Rhein,  of  New  York  City,  was,  as  far  as  I  am  able  to 
learn,  the  first  man  to  make  routine  use  of  the  radiograph  in  pulp  canal 
work. 

The  advantages  in  using  the  radiograph  in  this  connection  are  as  fol- 
lows :  Much  guesswork  is  eliminated — we  know  what  we  are  doing. 
If  the  canal  is  tortuous,  and  we  start  through  the  side  of  the  root,  the 
radiograph  shows  us  the  mistake,  keeps  us  from  making  a  perforation, 
and,  in  many  cases,  enables  us  to  follow  the  canal  to  the  true  apex.  If 
the  root  is  unusually  short  the  radiograph  keeps  us  from  going  through 
the  apex,  and  if  it  is  unusually  long  it  keeps  us  from  making  the  error  of 
not  penetrating  the  canal  far  enough.  The  radiograph  shows  patients 
just  what  is  being  done  for  them. 


178 


DENTAL   RADIOGRAPHY 


Fig.    175.      The   arrow  points   to   a   pulp   stone   in   the   pulp   chamber   of   an   upper   second  molar. 

The  blacks  and  whites  in  this  half-tone  are  as  they  appear  in  the  negative,  the  pulp  stone  a  light 

area   more   or  less  surrounded  by   dark. 


Fig.  176. 


Fig.  177. 


Fig.  176.     The  arrow  points  to  a  small  pulp  stone  in  the  pulp  chamber  of  a  lower  first  molar. 
Fig.  177.      Pulp  stones  throughout  the  canals  in  the  lower  central  incisors.     Also  small  stones  in 

the  lateral  incisors. 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY     179 

Having  observed  quite  a  large  number  of  radiographs  in  the  last  few 
years,  allow  me  to  state  that  many,  altogether  too  many  in  our  profession, 
fail  to  enlarge  and  fill  to  their  apices  all  canals  which  really  could,  and 
should,  be  so  treated.  There  are,  perhaps,  some  cases  where  the  buccal 
canals  of  upper  molars  and  the  mesial  canals  of  lower  molars  simply  can- 
not be  enlarged  to  their  apices.  But  this  fact  is  no  excuse  for  enlarging 
and  filling  only  the  upper  third  of  such  canals.  The  stock  excuse  for 
poor  canal  work  is  "'  our  patients  will  not  pay  a  fee  sufficiently  large 
to  enable  us  to  give  the  necessary  time  to  the  work."  But  do  those 
who  thus  excuse  themselves  really  give  their  patients  any  choice  in 
the  matter!^  If  one  should  show  a  patient  a  radiograph  demonstrating  tht 
fact  that  he  had  only  penetrated  the  canals  about  one-third  their  length 
then  explain  why  he  should  go  farther,  and  why  it  would  take  time  to 
do  so,  would  the  patient  say.  "  Oh !  let  'er  go,"  or  would  he  or  she  say, 
"  I  v/ant  done  whatever  is  best.''  " 

It  is  difficult  to  radiograph  the  buccal  roots  of  upper  molars,  particu- 
larly second  and  third  molars. 

i3«    to  Determine  lUbetber  an  Opening  Ceading  from  a  Pulp  Chamber  Be  a 
Canal  or  a  Perforation. 

When  one  opens  the  tooth  himself,  and  does  not  use  a  small,  round 
bur  on  the  floor  of  the  pulp  chamber,  he  may  feel  certain  that  any  open- 
ing found  must  be  a  canal.  But  in  cases  where  the  pulp  chamber  has 
been  opened  by  another  operator,  it  is  often  impossible  to  decide  whether 
an  opening  leading  from  the  pulp  chamber  be  the  mouth  of  a  canal  or  a 
perforation  through  the  tooth.  Likewise  in  cases  where  decay  has  attacked 
the  walls  and  floors  of  the  pulp  chamber,  almost  destroying  them,  it  is 
sometimes  difficult  to  differentiate  between  a  canal  and  a  perforation. 
Pass  a  wire  through  the  opening  and  make  a  radiograph. 

A  wire  passing  to  the  mesial  through  a  perfora 
tion  in  the  upper  first  molar. 


Tifl.  174. 


14.   Tn  Cases  of  Pulp  Stones  (nodules). 

There  has  been  a  great  deal  of  dispute  as  to  whether  or  not  pulp 
stones  can  be  shown  radiographically.  The  right  answer  is  in  the  affirm- 
ative 

The  appearance  of  the  pulp  stone  in  the  upper 
second  molar  is  typical.  Though  it  can  be  seen 
clearly  in  the  print  now  before  me  I  can  only  hope 
that  it  will  appear  in  the  halftone. 


fifl.  175. 


l8o 


DENTAL   RADIOGRAPHY 


Tifl,   176. 


Case  one  of  neuralgia.  The  radiograph  shows 
a  pulp  stone  in  the  lower  first  molar  at  the  mouth 
of  the  mesial  canal. 
Experience  in  the  practice  of  radiodontia  has  taught  me  that  there 
are  many  more  pulp  stones  in  teeth  than  I  had  thought.  Indeed  I  find 
myself  wondering,  after  observing  great  numbers  of  them  which  are 
not  causing  pain,  if  pulp  stones  ever  cause  pain.  And  then  I  see  a  case 
of  neuralgia,  or  earache,  in  which  the  radiograph  reveals  the  presence 
of  a  pulp  stone  which  is  removed  on  suspicion  and  lo !  the  patient  gets 
well. 


178 


Fig.  179 


Fig.    178. 


The    arrow    points    to    what    might   be    mistaken    for    a    pulp    nodule.      The    shadow 

is,  however,  a  filling  on  the  buccal  at  the  cervical. 
Fig.  179.      Simple  occlusal  filling  in  the  molar,  encroaching  on  the  pulp. 

Considering  the  common  occurrence  of  pulp  stones  it  is  certainly 
unwise  to  remove  them  whenever  found.  On  the  other  hand  it  is  some- 
times imperative  that  they  be  removed  in  cases  of  obscure  neuralgias 
and  neuritises. 

Intermittent,  intense  pain  in  region  of  chin  ex- 
Tifl.  177.  tending  backward   to   temporo-mandibular   articula- 

tion. In  this  case  the  pulp  stones  had  caused  death 
of  the  pulp  in  the  two  central  incisors.  Efforts  to  remove  the  stones 
from  these  teeth  met  with  failure  and  the  teeth  were  extracted.  The 
pulp  stones  in  the  lateral  incisors  were  removed.     Result :  A  cure. 

In  this  radiograph  the  arrow  points  to  a  shadow 
TiS.  17$.  which  was  mistaken  for  a  pulp  stone.     The  shadow 

is,  however,  not  a  pulp  stone,  it  is  a  small  filling  on 
the  buccal  surface  at  the  cervical. 

Fig.  178  is  indistinct,  not  because  the  detail  of  the  original  negative 
has  been  lost  in  the  process  of  making  the  half-tone,  as  frequently  occurs, 
but  in  this  case  because  the  original  negative  was  not  well  made.  It  was 
made  many  years  ago  when  the  art  of  radiodontia  was  so  young  we 
scarcely  had  an  idea  of  what  constituted  a  good  radiograph.  It  is,  to 
put  it  mildly,  an  unnecessary  risk  to  make  a  diagnosis  from  a  radiograph 
as  lacking  in  detail  as  Fig.  178. 

15.   Tn  Cases  of  Secondary  Dentin  Being  Deposited  and  Pinching  tbe  Pulp 

This  use  was  recently  suggested  in  a  dental  magazine  by  Dr.  Cryer. 
Such  a  condition  as  the  one  referred  to  might  exist  and  be  responsible  for 
neuralgia  or  other  nerve  disorders.     Likewise  it  could  probably  be  ob- 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY     i8i 

served  radiographically.     At  the  present  time,  however,  I  am  unable  to 
show  a  radiograph  of  such  a  case. 

16.   Co  Cearn  if  tbe  Tilling  In  the  Crown  of  a  Cootb  encroaches  on  tbc  Pulp. 

Case :    Neuralgic  pains  in  the  lower  left  side  of 
7lfl.  179  face.     Thought  to  be  due  to  a  necrotic  condition  of 

the  bone  in  the  region  of  the  lower  first  molar,  which 
had  recently  been  extracted.  A  radiograph  (Fig.  179)  shows  the  bone 
healthy.  The  simple  occlusal  filling  in  the  second  molar  penetrates  into 
the  pulp  chamber.  This  filling  was  removed,  and  the  semi-vital  pulp 
devitalized,  removed,  and  the  canals  filled.  The  result  was  an  immediate 
and  complete  recovery. 


Fig.   ISO  Fig.   181 

Fig.  180.  The  first  bicuspid  seems  to  hold  a  disto-occlusal  filling.  This  appearance  is  due 
to  a  slight  irregularity — a  slight  lapping  of  the  teeth.  The  filling  which  appears  to  be  in 
the    distal    of   the    first    bicuspid    is    in    the    mesial    of   the    second   bicuspid.      The    simple    occlusal 

filling   in   the   first  bicuspid  encroaches   into   the   pulp   chamber   slightly. 

Fig.    181.      The    same    as    Fig.    ISO    with    the    diseased    area    at    the    apex    of    the    first    bicuspid 

outlined,   to   enable   the   reader   to   see   it   better   in   Fig.    ISO. 

17.   Tn  0a$c$  of  teetb  with  Carge  metal  Tillinss  or  Shell  Crowns  mhich  Do 
not  Respond  to  the  Cold  test,  to  Eearn  if  the  Canals  J\n  Tilled. 

Case :  Slight  swelling  and  pain  in  the  lower 
TiflS.  l$0  and  ISl  bicuspid  and  first  molar  region.  The  patient  stated 
that  this  condition  had  occurred  and  recurred  many 
times  in  the  past  five  years.  At  no  time  had  the  swelling  been  great,  and 
the  pain  was  never  severe.  The  slight  swelling  and  an  annoying  pain 
would  last  for  a  few  days,  then  disappear  for  a  month  or  so.  There  was 
no  discharging  sinus.  The  first  molar  bore  a  gold  shell  crown,  the  second 
bicuspid  held  a  large  mesio-occluso-distal  amalgam  filling,  and  the  first 
bicuspid  had  a  small  filling  of  amalgam  in  the  occlusal  surface.  The 
three  teeth — the  first  molar  and  the  two  bicuspids — were  isolated  one  at  a 


l82 


DENTAL  RADIOGRAPHY 


time  and  tested  with  cold  water.  The  patient  was  uncertain  as  to  whether 
he  received  any  sensation  when  the  cold  was  applied  to  the  shell-crowned 
molar,  but  thought  that  he  did.  The  second  bicuspid  responded  well,  and 
the  first  bicuspid  did  not  respond  at  all.  This  seemed  to  indicate  a  vital 
pulp  in  the  molar  and  second  bicuspid,  and  a  devitalized  one  in  the  first 
bicuspid.  But,  when  looking  for  a  dead  pulp,  one  would  naturally  sus- 
pect either  the  molar  with  the  shell  crown,  or  the  second  bicuspid  with 
the  large  filling,  instead  of  the  first  bicuspid  with  the  small  occlusal  filling 


Fig.    182.      The     roots     of    the     shell     crowned     first     molar     are     not     properly     filled.       Only     the 

upper  third   of   the    distal   canal   is   filled  and   the   mesial   canals    are   not   filled   at    all.      The   tooth 

was    sore    and    caused    annoying    neuralgic    pains. 


The  temperature  test  is  a  valuable  one,  but  it  cannot  be  depended  upon 
absolutely.  A  radiograph  (Fig.  i8o)  was  made.  It  shows  the  canals  of 
the  molar  and  second  bicuspid  unfilled.  The  tissues  at  the  apices  of  the 
roots  of  these  teeth  are  healthy,  which,  together  with  the  positive  reaction 
to  the  cold  tests  indicates  that  their  pulps  are  vital  and  healthy.  The 
simple  occlusal  filling  in  the  first  bicuspid  enters  the  pulp  chamber  slightly, 
the  canals  of  the  tooth  are  unfilled,  and  the  light  area  at  the  apex  of  the 
root  indicates  disease  (inflammation)  of  the  bone  in  that  region.  These 
things,  together  with  the  fact  that  the  tooth  did  not  react  to  the  cold  test, 
indicate  a  putrescent  pulp  in  the  first  bicuspid.  The  tooth  was  opened, 
and  the  diagnosis  confirmed. 

In  practice,  case  after  case  presents,  the  patient 
Tffl.  I$2.  complaining  of  a  slight  soreness  or  annoying  pain  in 

the  region  of  a  shell-crowned  tooth,  or  a  tooth  with 
a  large  metal  filling  in  it.  The  tooth  fails  to  respond  to  the  cold  test,  and 
we  suspect  that  the  canals  are  poorly  filled,  or  perhaps  not  filled  at  all. 
Are  we  justified  in  removing  the  crown  or  filling  to  examine  the  canals? 
Before  the  radiograph  came  into  use  we  were,  but  not  to-day.  It  is  not 
fair  to  your  patient  nor  yourself  to  remove  a  can:il  filling  unless  you  can 
improve  on  the  operation.     Fig.   182  is  a  radiograph  of  a  case  of  the 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY     183 


class  just  alluded  to.  The  canal  filling  in  the  shell  crowned  lower,  first 
molar  is  so  imperfect,  it  should  not  be  difficult  to  improve  the  operation. 
Let  me  give  a  word  of  warning,  however:  Goodness  knows  it  is  hard 
enough  to  open  canals  to  the  end  when  you  are  the  one  who  opens  the 
tooth  for  the  first  time,  but,  when  there  has  been  a  previous  unsuccessful 
effort  at  canal  filling,  your  difficulties  may  be  multiplied  a  hundred-fold. 
Make  no  promise  of  success.  Note  the  slight  cervical  bone  destruction 
between  first  and  second  molars,  due  to  poorly  contoured,  poorly  fitting 
shell  crown. 


Fig.  183  Fig.  184 

Fig.    183.      Wire    just    penetrating    the    apical    foramen.       Showing    that    the    apical    sensitiveness 

is    not    due    to     an     unremoved,    undevitalized    remnant     of     pulpal     tissue. 

Fig.    184.     The    wire    in    the    canal    of    the    lateral    fails    to    reach    the    apex,    proving    that    the 

apical   sensitiveness   is   due   to  an   unremoved,   undevitalized    remnant   of   pulpal   tissue. 

1$.    Co  team  if  Hpical  Smltlwcness  Ts  Due  to  a  Earge  Hplcal  Torawen  or  an 
Unremoved,  Unaevitalized  Kemnant  of  Pulp. 

In  the  treatment  of  teeth  we  often  pass  the 
Tigs.  1$3  and  1$4.  broach  into  the  canal  until  we  reach  what  we  know 
must  be  the  neighborhood  of  the  apex,  when  pain  is 
produced.  It  is  often  difficult  to  decide  whether  this  pain  is  due  to  some 
remaining  vital  pulp  tissue  in  the  canal,  or  the  penetration  of  the  broach 
through  the  apex.  Fig.  183  is  from  such  a  case.  The  wire  passing  to 
the  point  of  sensitiveness  goes  through  the  apical  foramen,  and  so  proves 
that  the  sensitiveness  is  not  due  to  unremoved,  undevitalized  pulp  tissue. 
In  Fig.  184  the  wire  reaching  the  point  of  sensitiveness  fails  to  reach  th^ 
apex,  proving  that  the  sensitiveness  is  caused  by  an  unremoved,  unde- 
vitalized remnant  of  pulp. 

Let  us  stop  to  consider  how  this  question  of  whether  or  not  we  are 
penetrating  the  apex  is  decided  when  radiographs  are  not  used.  We  pump 
phenol  or  some  other  obtundent  into  the  canal,  working  our  broach  farther 


1 84 


DENTAL  RADIOGRAPHY 


and  farther  until  we  strike  the  end  of  the  canal  ending  in  a  blind  alley,  or 
go  so  far  into  the  apical  tissues  we  know  that  no  tooth  root  could  be  as 
long  as  the  distance  we  are  penetrating.  The  use  of  the  radiograph  saves 
all  this  guesswork,  obviates  the  necessity  of  causing  considerable  pain  and 
is  a  time-saver. 

19.   Tn  €<i$e$  of  ebronic  Pericementitis  (Came  tootb). 
A  putrescent  pulp  is  the  most  common  cause  for  pericementitis,  either 
chronic  or  acute.    Therefore,  when  the  affected  tooth  is  crowned  or  filled, 
as  it  almost  always  is  in  chronic  pericementitis,  radiographs  should  be 


Fig.  185  Fig.  186 

Fig.  185.  Gutta-percha  canal  filling  in  the  upper  lateral  passing  through  the  side  of  the  root 
to  the  distal.  The  canal  filling  also  penetrates  the  apical  foramen.  The  light  area  to  the 
mesial    along    the    apical    third    of    the    root    indicates    an    abscess.      The    mesial    surface    of    the 

root   is   roughened   in    the    region    of  the   abscess.       (Radiograph   by    Lewis   of    Chicago.) 

Fig.    186.     Canal    filling    penetrating    the    tissues    between    the    roots    of    the    lower    first    molar. 

(Radiograph    by    Kells,    Jr.    of    New    Orleans.) 


made  to  learn  whether  the  canals  are  properly  filled,  and  treatment  may 
be  rendered  accordingly.  Fillings  and  crowns  without  contact  points,  or 
fillings  with  bad  gingival  margins,  or  crowns  which  do  not  fit  well  at  the 
cervix  or  penetrate  beneath  the  gum  margin  into  the  peridental  membrane, 
are  sometimes  the  causative  factors  in  chronic  pericementitis.  These 
things  may  be  detected  usually  without  the  aid  of  the  radiograph.  Often, 
however,  a  radiograph  will  demonstrate  the  fault  in  a  very  convincing 
manner. 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY     185 

Figs.  185  and  186  demonstrate  lesions  that  might 

..  J     .  be  responsible  for  chronic  pericementitis,  which  could 

Tifls.  i$5  and  i$6. 

not  be  detected  by  any  means  other  than  the  use  of 

the  radiograph. 


Fig.  187.     The  arrows  point  to  a  small  abscess   (the  light  area)   at  the  apex  of  a  lower  centra 
incisor.      None   of  the  lower  anterior  teeth  have   cavities  in   them. 


Fig.  188  Fig.  189 

Fig.   18S.      Evidence  of  bone   change   at   apex   and   downward   along   distal   side   of   cuspid — the 

tooth  with  the  post  in  the  otherwise  unfilled  canal.     Piece  of  root  in  first  bicuspid 

region.     Suspicious  spot  in  apical  region  of  second  bicuspid. 

Fig.    189.      Abscess    of   central    incisor  .with    considerable    bone    destruction    in    apical    region    of 
missing  approximating  lateral  incisor. 

20»    Tn  0a$c$  of  Jllpcolar  J1b$ce$$  to  Determine  Ulbicb  tooth  is  Responsible 

for  tbe  Jlbscess, 

Case :  A  pus  sinus  opening  on  the  labial  between 

Tig.  i$7.  the    lower   central    incisors   near   their   apices.      All 

of   the   lower   anterior   teeth   sound   and  apparently 


i86  DENTAL  RADIOGRAPHY 

healthy.  Fig.  187  shows  which  tooth  is  responsible  for  the  abscess. 
This  tooth  was  treated  and  the  abscess  cured.  The  light  area  to  which 
the  arrow  points,  about  the  apex  of  the  central,  represents  the  abscess 
cavity.  Acute  abscesses  cannot  always  be  shown  in  radiographs,  because 
there  may  not  be  sufficient  destruction  of  bony  tissue.  Chronic  abscesses, 
which  have  become  acute,  can,  of  course,  be  shown  radiographically. 

Take  for  example  such  a  common  case  in  the  practice  of  dentistry 
as  a  bridge  with  a  fistula  pointing  above  a  dummy.  One  does  not  know 
before  a  raidiographic   examination   is  made   whether  there   is   a   piece 


Fig.  190.  Abscess  at  apex  of  lower  second  bicuspid.  The  tooth  carries  a  gold  shell  crown. 
Canal  is  not  filled.  The  inferior  dental  canal  can  be  seen  plainly  in  this  radiograph — 
light  streak  between  two  dark  lines  along  the  lower  border  of  the  mandible. 


of  tooth  root  above  the  dummy,  whether  one  abutment  tooth  is  abscessed 
or  the  other,  or,  for  that  matter,  whether  or  not  all  of  these  things  exist. 
Thus  one  does  not  know  how  to  treat  the  case  at  all  and  must  depend 
upon  raidiographic  examination  before  any  intelligent  action  can  be  taken. 

Case :      Fistula     pointing     above     upper     first 

Tig.  ISS.  bicuspid  dummy.     The  radiograph  shows  a  piece  of 

the  root  of  the  first  bicuspid,  an  abscess  area  at  the 

apical  and  to  distal  of  the  cuspid,  and  a  suspicious  area  in  the  apical 

region  of  the  second  bicuspid. 

Treatment  indicated :  Removal  of  bridge.    Removal  of  piece  of  tootb 
root.     Treatment  of  cuspid :  Testing  of  second  bicuspid  for  vitality. 

Case :    Fistula  pointing  above   lateral  dummy. 

fig.  1$9.  The    radiograph    shows    a    rarified    area    above    the 

dummy    communicating    with    the    crowned    central 

incisor.     The  cuspid  is  not  involved  in  the  abscess  ;  it  has  a  vital  pulp. 

The  missing  lateral  was  probably  abscessed.  Its  extraction  did  not  eradicate 

the  pus  sinus  at  its  apex  because  the  central  fed  infection  to  this  sinus. 

Treatment :  Disinfection  and  filling  of  canal  of  central.     Curettement 
of  pus  sinus. 

Fistula    just    in    front    of    lower    third    molar. 
Ti9.  190,  The   third   molar    free   of   carious   cavities.      I    sus- 

pected  a   piece   of   unremoved   root   of   the  missing 
second  molar  to  be  responsible  for  the  suppuration.    A  radiograph  (Fig. 


THE    USES  OF   THE  RADIOGRAPH  IN  DENTISTRY   187 

190)  was  made.  It  demonstrates  the  absence  of  any  piece  of  tooth  root, 
and  shows  a  large  abscess  at  the  apex  of  the  shell-crowned  second  bicus- 
pid. The  bicuspid  was  opened  and  an  antiseptic  solution  forced  through 
the  tooth  and  out  through  the  fistulous  opening  in  front  of  the  third 
molar. 

The  radiograph  does  not  show  the  fistulous  tract  leading  from  the 
bicuspid  backward  toward  the  third  molar.  The  probable  reason  for  this 
is  that  the  tract  passes  along  between  the  bone  and  periosteum.  There- 
fore, there  is  very  little  destruction  of  bony  tissue  throughout  its  course. 

Recently  the  following  case  presented :  Fistulous  opening  on  the 
labial  over  the  apex  of  a  perfectly  sound  upper  cuspid.  The  first  bicuspid 
apparently  healthy  save  for  a  small,  faulty,  amalgam  filling.  The  proxi- 
mating  lateral  shell  crowned.  I  suspected  the  crowned  lateral  to  be  the 
seat  of  the  trouble.  A  radiograph  was  made,  and  showed,  to  my  surprise, 
that  the  lateral  was  perfectly  healthy  and  its  canal  well  filled.  A  radio- 
graph of  the  first  bicuspid  was  made  and  showed  an  abscess  and  unfilled 
canals.  I  do  not  print  radiographs  of  this  case,  because  one  of  them,  the 
one  showing  the  abscess,  has  been  mislaid.  I  record  the  case  because  it  is 
one  the  like  of  which  a  person  may  run  across  any  day  in  practice. 


21.    Tn  Gases  oT  Hlccolar  Jibsccss  to  Determine  the  extent  of  tbe  Destruction  of 
tissue— Bony  and  Cootb 

Case  :   Shell-crowned,  lower  first  molar.   Chronic 
Tig.  19i.  abscess  of  several  years'  standing.     The  crown  was 

removed,  and  the  tooth  treated.  The  flow  of  pus 
stopped.  The  canals  were  filled  and  the  crown  reset.  In  about  a  month 
there  was  a  recurrence  of  pus  production.  A  radiograph  (Fig.  191)  was 
made,  and  shows  both  roots,  especially  the  mesial,  badly  absorbed.  The 
canal  fillings  penetrate  into  the  area  of  diseased  bone.  I  advised  extrac- 
tion. A  most  peculiar  fact  in  this  case  is  the  great  destruction  of  tooth 
structure,  and  the  comparatively  slight  destruction  of  the  alveolar  bone ; 
the  reverse  of  what  is  usually  found.  Not  only  is  there  little  destruction 
of  bone,  but  bony  tissue  seems  actually  to  have  filled  in  the  space  formerly 
occupied  by  the  tooth  roots. 

One  of  the  most  perfectly  circumscribed  alveo- 

Ti3.  192.  lar  abscesses  I  have  ever  seen.     The  abscess  occurs 

at  the  apices  of  the  roots  of  the  upper  first  bicuspid. 

Notice  how  the  two  roots  extend  into  the  abscess  cavity.     The  very  light 

shade  of  bone  to  the  distal  of  the  bicuspid  is  diseased,  somewhat  carious, 

but  will  regain  normal  vitality  in  all  probability  when  thorough  drainage 


i88  DENTAL  RADIOGRAPHY 

of  the  abscess  is  obtained.     A  case  like  this  should  yield  to  treatment 
without  extraction.     Root  resection  is  indicated. 

A  very  large  abscess  involving  the  upper  central 

fig.  193,  and  lateral  incisors  of  one  side.    I  am  unable  to  learn 

what  treatment  was  given  in  this  case.     Basing  my 

judgment  on  the  appearance  of  the  radiograph,  without  any  clinical  knowl- 


Fig.   191  Fig.    192 

Fig.    191.     -Both    roots    of    the    shell-crowned,    lower,    first    molar    badly    absorbed,    especially    the 

mesial.      Canal  fillings  extend  beyond  the  ends   of  the  roots. 
Fig.   192.      An  almost  perfectly  circumscribed   abscess   about  the   roots   of  an   upper   first   bicuspid. 
Note  how  the  roots   extend  into   the  abscess  cavity.      (Radiograph   by  Blum,   of  New   York   City.) 

edge, of  the  case,  I  would  say  that  the  lateral  should  be  extracted,  and 
the  opening  so  made  into  the  abscess  cavity  enlarged  to  the  distal  to  such 
an  extent  as  to  permit  a  thorough  curettement  of  the  suppurating  sinus. 
(This  would  necessitate  removal  of  the  bridge  from  first  bicuspid  to 
cuspid.)  Or,  perhaps  an  opening  sufficiently  large  to  permit  thorough 
curettement  and  drainage  could  be  made  through  the  external  alveolar 
plate  and  the  lateral  conserved.  At  any  rate,  knowing  that  the  opening 
into  a  pus  sinus  to  drain  and  curette  it  thoroughly  must  vary  directly 
according  to  the  size  of  the  sinus,  we  can  see  that,  in  this  case,  the  open- 
ing must  be  quite  large.  Such  an  abscess  could  not  be  drained  sufficiently 
well  through  pulp  canals. 

Fig.   194  shows  how  utterly  futile  it  would  be 

fig,  194,  to  attempt  to  treat,  and  retain  in  the  mouth,  such  a 

tooth  as  is  shown  in  the  radiograph.  Such  a  condi- 
tion could  not  have  been  diagnosed  by  means  other  than  the  use  of  the 
X-rays.  The  small,  dark  streak  through  the  tooth  is  a  wire.  Note  the 
great  destruction  of  the  tooth  root  and  the  carious  condition  of  the  sur- 
rounding bone. 

Case :    Sinus  opening  near  the  apex  of  an  upper 

Tifl.  195.  central  incisor.    The  tooth  did  not  yield  to  treatment. 

It  was  treated  on  the  assumption  that  there  was  con- 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY     189 

siderable  destruction  of  bone,  and  powerful  stimulating  corrosives,  like 
phenolsulphonic  acid,  were  forced  beyond  the  apex.  That  such  treatment 
was  improper  is  demonstrated  by  the  radiograph  (Fig.  195),  which  shows 
that  there  is  very  little  bone  destruction.  Accordingly  the  more  radical 
line  of  treatment  was  dropped,  the  sinus  injected  with  bismuth  subnitrate 
paste,  a  mild  antiseptic  sealed  in  the  canal,  and  the  tooth  allowed  to  rest 
unmolested  for  ten  days,  at  the  end  of  which  time  all  pathological  symp- 
toms had  disappeared. 


Fig.   193  Fig.  194  Fig.   195 

Fig.    193.      Very   large   abscess  involving   the   lateral   and   central,   and    extending  almost   to   the 

apex  of  the  first  bicuspid.      (Radiograph  by   Peabody,   of   South   Orange,   N.   J.) 

Fig.  194.     Absorption   of  the  root  and  surrounding  bony  tissue.     A  wire  is  seen  passing  into  the 

canal.      (Radiograph  by  Blum,   of  New  York   City.) 

Fig.  195.     A  very  small  abscess  cavity  at  the  apex  of  the  central  with  the  wire  in  it. 


22.   Tn  0asc$  of  JllDColar  Jlbscws  to  team  Iiow  many  Ccetb  are  Tnuolved. 

I  recall  having  treated  an  abscessed  central  in- 
Tifl.  196.  cisor  for  a  month  without  effecting  a  cure,  or  even 

much  improvement.  The  apical  foramen  was  well 
opened,  and  antiseptic  and  stimulant  washes  could  easily  be  forced 
through  the  tooth  and  out  through  the  fistulous  opening  on  the  gum,  as- 
suring me  that  I  had  good  drainage.  The  lateral  at  the  side  of  the  cen- 
tral did  not  respond  to  the  cold  test,  but  neither  did  any  other  tooth  in 
the  patient's  mouth.  Despite  the  fact  that  it  was  a  sound  tooth,  I  opened 
into  the  lateral,  removed  the  pulp,  which,  while  devitalized,  was  not  badly 
putrescent,  enlarged  the  apical  foramen,  and  found  that  washes  forced 
into  the  lateral  came  out  both  the  fistula  and  central.  While  the  case  is 
not  the  same,  the  conditions  which  I  then  combated  in  the  dark  (I  did 
not  use  the  X-rays  in  my  practice  at  this  time),  are  shown  in  Fig.  196. 
An  abscess,  involving  both  central  and  lateral,  is  shown  by  the  light  area 


igo 


DENTAL  RADIOGRAPHY 


about  and  above  their  apices.    In  this  case  the  canal  of  the  central  is  only 
partially  filled,  and  the  lateral  canal  not  filled  at  all. 

An  abscess  pointing  in  the  palate.    A  radiograph 

Tifl.  197.  (Fig.  197)  was  made  to  determine  which  tooth  was 

responsible.     The   central,   lateral,   cuspid  and   first 

bicuspid  were  suspected.     The  radiograph  shows  that  all  of  these  teeth 


Fig.   196  Fig.   197 

Fig.  196.     Abscess  involving  the  central  and  lateral  incisors.     The  canal  of  the  central  is  partiall-y 

filled.      (Radiograph  by  Lewis,  of  Chicago.) 

Fig.   197.     A  large  abscess  involving  the  central,  lateral  and  cuspid. 


except  the  first  bicuspid — i.e.,  the  central,  lateral  and  cuspid — are  in- 
volved. The  abscess  was  treated  through  all  three  teeth,  but  did  not 
yield  to  this  treatment.  It  was  deemed  necessary  to  curette  the  sinus.  An 
opening  through  which  the  sinus  could  be  curetted  was  made  by  extract- 
ing the  lateral  root.  Perhaps  there  are  those  who  will  condemn  my 
surgery,  saying  the  tooth  should  have  been  conserved  and  the  opening 
made  Into  the  sinus  through  the  external  alveolar  plate. 

The  foregoing  was  written  five  years  ago.  It  is  unlikely  that  I 
would  be  criticised  to-day  for  extracting  the  lateral,  though  I  might  be 
criticised  for  not  removing  all  three  teeth  or  at  least  for  not  removing 
the  ends  of  the  roots  of  the  teeth  not  extracted. 

23.   Tn  Cases  of  Hbscess  of  multirooted  tectb,  to  Ccarn  at  the  Jlpex  of  lUhicb  Koot 

the  Abscess  exists. 

This  radiograph  shows  an  abscess  at  the  apex 
?ig.  19$.  of  the  mesial  root  of  a  shell-crowned,  lower  first 

molar.     The  canals  of  the  tooth  are  not  filled. 
There  is  so  much  definite  evidence  of  extensive  infection  about  the 
mesial  root  that  its  removal  is  indicated ;  the  distal  root  can  be  con- 


THE   USES  OF   THE  RADIOGRAPH  IN  DENTISTRY     191 

served.  Perhaps  disinfection  of  the  area  about  the  mesial  root  could 
be  accomphshed  by  ionization.  The  ionization  method  of  disinfection 
is  comparatively  untried  but  it  seems  to  the  writer  to  hold  great  possi- 
bilities. 


Fig.   198  Fig.   199 

Fig.  198.     Abscess  at  the  apex  of  the  mesial  root  of  the  shell-crowned,  lower,  first  molar.     The 

canals  of  the  tooth  are  not  filled.      (Radiograph  by  Blum,   of  New  York   City.) 
Fig.    199.      Large   abscess   involving  both   roots  of   the  lower   first   molar  and   probably   both   roots 
of   the    second   molar.      The    distal    canal    of   the    first   molar   is    partially    filled.      (Radiograph    by 

Ream,  of  Chicago.) 


A  large  abscess  involving  both  roots  of  the  lower 

Tifl.  199.  fi^st  molar  and  probably  both  roots  of  the  second 

molar.     Without  a  history  of  the  case  to  guide  me. 

I  should  say,  judging  from  the  appearance  of  the  radiograph,  the  first 

molar  should  be  extracted  and  diagnostic  exploration  of  the  second  molar 

should  be  made  to  learn  whether  or  not  its  pulp  is  vital. 

24.    Tn  Cases  of  Abscess  of  Crowned  teeth  to  Cearn  if  the  Canals  are  Properly  Tilled. 

It  is  a  common  occurrence  in  practice  to  have  a  patient  present  with 
a  pus  sinus,  discharging  in  the  region  of  the  apex  of  a  tooth  carrying  a 
crown.  If  the  canals  of  the  tooth  are  properly  filled,  we  should  treat  the 
sinus  through  the  external  alveolar  plate ;  if  the  canals  are  not  properly 
filled,  then  the  crown  should  be  removed  and  the  case  treated  through 
the  tooth — perhaps  through  the  external  alveolar  plate  also,  depending 
on  the  extent  of  the  destruction  of  tissue.  Whether  or  not  the  crown 
should  be  removed  is  determined  by  the  use  of  the  radiograph. 


192 


DENTAL    RADIOGRAPHY 


tion 


In  the  third  edition  of  his  Modern  Dental  Ma- 

Tig.  200.  tcria  Medica,  Pharmacology  and  Therapeutics,  Dr. 

Buckley  prints  Fig.  200,  and  the  following  descrip- 

Fig.  200  "shows  the  involvement  of  the  upper  central  and  lateral 


Fig.    200  Fig.    201 

Fig.  200.  Abscess  involving  the  upper  central  and  lateral  incisors.  There  was  tiut  one  fistulous 
opening  on  the  labial.  Since  the  canals  of  central  and  lateral  are  both  properly  filled  the 
treatment  should  consist  simply  of  curettement  of  the  affected  area,  which,  of  course,  does  not 
necessitate    the    removal    of   the    post-porcelain    crowns    from    the    teeth.       (Radiograph    by    Ream, 

of   Chicago.) 
Dr.    Rhein    says    of    Fig.    201:    "This    is    a    typical    case    of    chronic    alveolar    abscess, 
which   for   years   had   been    erroneously   treated   for    pyorrhea." 


Fig.    201. 


Fig.  202.     Alveolar  abscess  wrongly  diagnosed  as  pyorrhea.     (Radiograph  by  Rhein,  of  New  York.) 


incisors  in  an  abscess.  Both  teeth  carried  perfectly  adjusted  porcelain 
crowns.  The  skiagraph  not  only  shows  the  involvement  of  both  teeth, 
but  also  that  the  roots  are  properly  filled.  The  treatment  here  is  purely 
surgical,  and  means  the  curettement  of  the  affected  area."  Had  the 
radiograph  not  been  used  the  operator  would,  in  all  probability,  have 
made  the  laborious  and  foolish  mistake  of  removing  the  crowns  on  the 
assumption  that  the  canals  were  not  properly  filled. 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY     193 

25.    n$  an  nm  in  Differential  Diagnosis  Between  Chronic  JJlpeolar  Abscess  and 
Pyorrhea  Jllpeolaris. 

When  a  chronic  alveolar  abscess  discharges  about  the  neck  of  a  tooth 
the  case  so  closely  simulates  calcic  pyorrhea  alveolaris  that,  without  using 
the  radiograph  or  opening  into  the  affected  tooth,  the  operator  cannot 
make  a  definite  diagnosis. 


Fig.   203 


Fig.    204 


Fig.  303.     Absorption  of  the  bone  around  the  molar  due  to  pyorrhea  alveolaris.     The   tooth   has 

no   bony  attachment  at  all.      (Radiograph   by  Ream,   of  Chicago.) 
Fig.  204.     Absorption  of  the  bony  -tissue  due  to  pyorrhea  alveolaris. 


This  is  a  case  from  the  practice  of  Dr.  M.  L. 
fig.  201,  Rhein,  of  New  York  City.     Dr.  Rhein  says :     "This 

is  a  typical   example  of  a  chronic  alveolar  abscess, 
which  for  years  had  been  erroneously  treated  for  pyorrhea." 

Fig.    202    represents    another    case    from    the 

Tig.  202.  practice    of    Dr.    Rhein,    which    had    been    wrongly 

diagnosticated  as  pyorrhea.     The  lateral  incisor  was 

supposed   to   be   affected  by   pyorrhea,   but   after  making  a   radiograph. 

Fig.  202,  it  was  seen  that  the  real  trouble  was  an  apical  abscess,  the 

infection  arising  from  the  death  of  the  pulp. 


26.    to  Observe  Destruction  of  tissue  Due  to  Pyorrhea  Jllpeolaris. 

Other  factors  being  equal,  our  chances  of  curing 
Tig.  203,  pyorrhea  alveolaris  vary  inversely  according  to  the 

amount  of  destruction  of  alveolar  process  surround- 
ing the  affected  teeth.  Fig.  203  demonstrates  the  futility  of  treating 
and  attempting  to  conserve  the  molar  tooth.  All  of  the  bone  immediately 
surrounding  the  tooth  is  destroyed. 


194 


DENTAL   RADIOGRAPHY 


A  typical  case  of  extensive  loss  of  osseous  tis- 
Tig.  204.  sue  about  the  upper  anterior  teeth  due  to  pyorrhea 

alveolaris.      More  than  half   of   the  normal   attach- 
ment of  the  teeth  is  destroyed  due  to  the  loss  of  bone.     Compare  Fig. 


Fig.  205  Fig.   306 

Fig.   205.      Loss   of   osseous   tissue   about   a  lower  first   molar   due   to   pyorrhea.      The   distal   root 

has    no    bone    attachment    at    all    and    the    mesial    root    an    attachment    only    near    the    apex. 

The  mesial  root  seems  to  be  necrotic  or  carious,  but  it  is  not.      (See  Fig.  436C.) 

Fig.   206.      The   arrow  points   to   bit   of   calculus   on   the    distal    of   a   second   bicuspid.      The   light 
area  above  the  calculus  denotes  the  destruction  of  bone  and  represents  a  pyorrhea  pocket. 


204  with  Fig.  207  in  which  latter  case  the  osseous  tissue  in  the  cervical 
region  is  healthy. 

In  this  connection  it  should  be  borne  in  mind  that  the  extremely 
sharp  points  of  alveolar  process  between  the  teeth,  which  can  be  seen 
clearly  in  Fig.  207  about  the  lateral  incisor,  are  lost  with  age.  Thus 
care  should  be  taken  not  to  confuse  age  changes  with  the  disease  pyor- 
rhea alveolaris. 

A  lower   first   molar    affected    with   pyorrhea. 
fig.  205.  The  distal  root  is  entirely  denuded  of  pericemental 

membrane  and  bone  and  the  mesial  root  also,  save 
just  at  the  apical  fourth.     (See  Fig.  436C.)     Extraction  imperative. 


A  pyorrhea  pocket  on  the  distal  of   an  upper 
Tig.  206.  second  bicuspid.     There  is  but  slight  destruction  of 

bone.    The  most  remarkable  thing  about  this  picture 
is  that  it  shows  a  bit  of  calculus  on  the  distal  of  the  second  bicuspid. 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY     195 

27.    Tn  Cases  of  Pericemental  Hbscess. 

"Pericemental  abscesses  have  been  described  by  numerous  writers,  one 
of  the  best  papers  on  the  subject  being  that  by  Dr.  E.  C.  Kirk,  published 
in  the  Dental  Cosmos  for  November,  1900.  There  are  various  views  as 
to  the  etiology  of  this  condition,  but  the  main  point  of  interest  lies  in  the 
fact  that  pericemental  abscess  occurs  on  the  root  of  a  tooth  in  which  the 


Fig.  207  Fig.   208 

Fig.  207.  Pericemental  abscess  at  apex  of  upper  cuspid.  The  crowned  first  bicuspid  was  sus- 
pected, but  the   radiograpli   shows   an   abscess  at   apex   of   the   cuspid,    wliicli   was   soand   and   alive. 

(See  Fig.  459A.) 
Fis-   20s.      The  light  area  to  which  the  arrow  points  is  a  pericemental  abscess. 

pulp  is  still  alive,  a  fact  which  renders  a  true  diagnosis  sometimes  quite 
complex.  For  example,  a  patient  might  present  with  a  well  defined  fis- 
tula appearing  between  the  roots  of  two  teeth,  one  of  which  may  be 
perfectly  sound,  whereas  the  other  might  be  just  as  certainly  pulpless.  It 
would  be  quite  reasonable  for  the  operator  to  conclude  that  an  abscess 
originated  from  infection  coming  from  the  root  of  the  pulpless  tooth,  and 
to  treat  such  a  tooth,  it  might  be  necessary  to  remove  important  and  well 
constructed  work,  such  as  an  inlay  or  a  bridge  abutment.  A  radiograph, 
however,  will  disclose  that  the  abscess  involves  the  pericementum  of  the 
living  tooth,  and  thus  the  dentist  would  be  saved  the  mortification  of  un- 
necessarily destroying  the  inlay  or  abutment  attached  to  the  pulpless  tooth, 
and  the  patient  would  be  saved  the  annoyance  and  expense  involved  in 
such  a  misconstruction  of  symptoms. 

"From  the  practice  of  Dr.  M.  L.  Rhein  is  a  case 
fifl.  207.  of    this    character.      The    bicuspid    is    crowned    and 

might  have  been  suspected  as  the  cause  of  the  ab- 
scess, especially  as  in  the  radiograph  only  one  root  canal  filling  is  seen, 
but  the  history  of  the  case  made  this  impossible.    The  tooth  was  treated 


196  DENTAL  RADIOGRAPHY 

twelve  years  ago  for  an  abscess,  and  both  canals  were  perfectly  filled, 
as  can  be  seen  in  other  radiographs  of  the  case  in  the  possession  of  Dr. 
Rhein,  these  radiographs  being  taken  at  a  slightly  different  angle.  The 
tooth  having  remained  perfectly  comfortable  during  all  of  these  years, 
the  well  defined  abscess  disclosed  at  the  apex  of  the  cuspid  tooth  was 
diagnosed  as  a  pericemental  abscess.  The  tooth  in  question  was  abso- 
lutely sound,  having  no  filling  or  cavity  of  any  kind,  and  when  opened  the 
pulp  was  found  to  be  alive.  Also  there  was  no  taint  of  pyorrhea  in  this 
mouth.  This  diagnosis  was  confirmed  by  the  fact  that  the  removal  of 
the  pulp  from  the  cuspid  and  subsequent  treatment  through  the  canal 
effected  a  perfect  cure.*" 

Case :    A  sinus  discharging  near  the  apex  of  an 
Tlfl*  20s.  upper  cuspid.     The  cuspid  had  no  carious  cavity  in 

its  crown,  and  responded  to  the  cold  test.  A  radio- 
graph (Fig.  208)  was  made  and  shows  a  pericemental  abscess  on  the 
distal  side  near  the  apex  of  the  cuspid,  but  not  involving  the  apex,  and 
hence  was  not  involving  the  pulp. 

It  would  have  been  a  mistake  to  remove  the  pulp  from  the  cuspid 
because  it  was  not  involved.  An  incision  was  made  through  the  external 
alveolar  plate,  the  pus  sinus  was  thoroughly  curetted  and  then  filled  with 
bismuth  paste.     The  result  was  a  prompt  and  complete  cure. 

Buckley,  in  his  last  edition  of  his  Modern  Dental  Materia  Medica, 
Pharmacology  and  Therapeutics,  prints  a  radiograph  similar  to  Fig.  208. 
Before  the  radiograph  was  used,  in  the  case  reported  by  Dr.  Buckley,  the 
pericemental  abscess  was  diagnosed  as  an  alveolar  abscess,  due  to  a  dead 
pulp.  The  tooth  thought  to  contain  a  dead  pulp  was  opened,  and  a  vital 
pulp  found.  The  operators  who  handled  the  case  experienced  a  great  deal 
of  difficulty  in  removing  the  pulp,  nitrous  oxygen  anesthesia  being  re- 
sorted to  finally  to  accomplish  it.  After  removal  of  the  pulp  "the  tooth  (a 
central  incisor)  became  dark  blue  in  color."  In  concluding  the  report  of 
this  case,  Dr.  Buckley  says:  "The  patient  in  this  instance  was  a  lady, 
and  when  we  recall  that  the  tooth  involved  was  an  anterior  one,  the 
seriousness  of  the  mistaken  diagnosis  becomes  all  the  more  apparent." 

Compared  to  the  occurrence  of  alveolar  abscesses,  caused  by  in- 
fection from  dead  pulps,  pericemental  abscesses  are  extremely  rare. 

2$.  Tn  0a$e$  of  Persistent  Suppuration  Ulbicb  Do  not  Vield  to  tl)e  Usual  treatment. 

Case :     Girl  eighteen  years  old,  had  had  a  lower 

Tig.  209.  second  molar  extracted  two  months  previous  to  the 

time  when  she  presented  to  me  for  treatment.     The 

socket   from  which  the  second  molar  had  been  extracted  was  an  open 


*By  Dr.  R.  Ottolengui. 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY     197 

suppurating  sore.  The  patient  was  poor,  and,  wishing  to  spare  her  the 
expense  of  having  a  radiograph  made,  a  diagnosis  was  made  to  the  best 
of  my  abiHty  by  other  means — by  symptoms  and  instrumental  examina- 
tion. The  diagnosis  was  infection  by  some  particularly  virulent  pyo- 
genic organisms  and  a  slight  caries  of  the  bone.  I  was  unable  to  locate 
any  unremoved  piece  of  tooth  root.  The  socket  was  vigorously  curetted 
and  cauterized  with  phenolsulphonic  acid,  a  mouth-wash  prescribed,  and 
the  patient  instructed  to  return  in  three  days.     When  next  seen  there  was 


Fig.    209  Fig-    210 

Fig.    209.      An    unerupted   third   molar   wliicli    caused   sufficient   irritation    to    sustain    a    •suppurating 

wound   from   where   a   second   molar   was   extracted. 

Fig.    210.      A   case   of   persistent    suppuration    of   several   years'    standing.      The    radiograph    shows 

the   cause — an    impacted,    malposed    upper   cuspid.       (Radiograph    by    Lewis,    of    Chicago.) 

but  slight  improvement  in  the  objective  symptoms,  and  the  patient  re- 
ported that  there  had  been  no  abatement  in  pain  and  soreness.  The  lesion 
was  washed  thoroughly  with  an  antiseptic  solution,  and  the  patient  in- 
structed to  return  in  three  days.  When  seen  again  there  was  no  improve- 
ment over  what  had  existed  before  the  operation.  Wishing  to  get  a  more 
complete  and  reliable  history  of  the  case,  I  consulted  with  the  patient's 
physician.  He  had  treated  the  oral  lesion  before  the  case  came  to  me,' 
and  was  of  the  opinion  that  it  was  tubercular.  He  suggested  the  tuber- 
culin treatment.  A  radiograph  (Fig.  209)  was  made  to  make  sure  that 
there  was  not  a  piece  of  the  second  molar  still  in  the  jaw.  As  can  be 
seen,  there  is  no  piece  of  tooth  root  present,  but  what  we  do  see  is  an 
erupting  third  molar.  Perhaps  I  should  have  thought  of  the  third  molar 
as  a  cause  for  the  trouble.  But  I  did  not  until  the  radiograph  was  before 
me.  Believing  this  tooth,  in  its  effort  to  erupt,  to  be  responsible  for  a 
slight  irritation  and  the  consequent  suppuration,  the  soft  tissues  and  the 


198 


DENTAL   RADIOGRAPHY 


bone  covering  it  were  dissected  away.  The  result  was  immediate  im- 
provement. I  regret  that  I  cannot  definitely  report  a  complete  recovery, 
but  I  am  sure  it  occurred.  The  patient  left  the  city  about  a  week  after 
the  last  operation,  and  I  have  not  seen  nor  heard  from  her  since. 

I  have  already  referred  to  a  case  of  persistent 
Tifl.  210.  suppuration,  reported  by  Dr.  T.  W.  Brophy,  which 

did  not  yield  to  treatment  until  a  radiograph  dis- 
closed the  presence  of  a  supernumerary  tooth,  and  it  was  removed.  In 
answer  to  a  letter  of  mine,  asking  for  a  radiograph  of  the  case,  Dr.  Brophy 


Fig.   311  Fig.   21s 

Fig.  211.  Abscess  at  the  apex  of  the  shell-crowned,  second  bicuspid.  It  is  very  difficult  to 
observe  either  the  abscess  or  the  unfilled  canal  in  the  bicuspid  in  the  print,  though  both  show 
clearly  in  the  negative.     The  arrow  A  points  to'  the  abscess  at  the  apex  of  the  tooth.     The  arrow 

B  points  to  an  abscess  on  the  side  of  the  root,  caused  by  the  ill-fitting  shell-crown. 

Fig.   212.     Same  case  as   Fig.   211.     The  dark  shadow  is  bismuth   paste.     It  passes   from   the   apex 

of  the  upper  second  bicuspid  downward  and  towards  the  second  molar. 


informed  me  that  it  could  not  be  found,  and  enclosed  Fig.  210,  saying  it 
was  a  similar  case,  i.e.,  a  case  of  persistent  suppuration,  which  did  not 
yield  to  treatment  until  the  radiograph  showed  the  exciting  cause,  and  it 
was  removed.  The  history  of  the  case,  illustrated  in  Fig.  210,  is  about 
as  follows :  The  upper  lateral  became  abscessed.  It  was  treated,  and  the 
canals  filled.  Pus  continued  to  flow  from  a  fistulous  opening  on  the  labial. 
The  abscess  was  treated  through  the  alveolar  plate,  but  without  success. 
A  radiograph  was  made.  I  quote  Dr.  Brophy.  'Tt  (the  radiograph) 
exhibits  a  cavity  in  the  bone,  absorption  of  the  apex  of  the  root  of  the 
lateral,  as  well  as  the  apex  of  the  root  of  the  adjacent  central  tooth. 
Above  is  an  impacted  cuspid  lying  in  a  nearly  horizontal  position.  To 
cure  a  case  of  this  character  calls  for  most  careful  study,  deliberation 
and  action.  The  course  to  pursue  is  largely  dependent  upon  the  condition 
of  the  other  teeth  forming  the  upper  denture.  In  a  young  person,  the 
removal  of  the  lateral  incisor  root,  which  is  crownless  and  diseased,  and 
the  gradual  moving  downward  into  its  place  of  the  cuspid  would  be  the 
most  desirable  procedure.     If  the  patient  is  in  middle  life,  and  the  teeth 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY     199 

badly  diseased  and  loose,  as  the  teeth  here  represented  are,  I  would  rec- 
ommend the  removal  of  the  diseased  teeth,  diseased  bone,  and  impacted 
tooth.  The  history  of  this  case,  with  suppuration  extending  over  a  period 
of  several  years,  so  beautifully  and  clearly  illustrated  by  the  use  of  the 
Roentgen  photograph,  impresses  us  with  the  inestimable  value  of  this 
means  of  reaching  a  diagnosis." 

29.   to  Observe  the  Course  of  tbe  Tistulows  tract. 

Dr.  Emil  Beck,  of  Chicago,  was  the  first  to  use  bismuth  paste*  in 
radiography.  The  paste  is  opaque  to  X-rays.  Thus  Dr.  Beck  would 
inject  a  fistula  and  abscess  cavity,  then,  with  the  paste  injected,  make  a 


Fig.  213.     Bismuth  paste  injected  into  fistulous   opening  just  above  tlie  first  bicuspid  dummy  and 
nearly   filling  a   very  large  abscess   cavity.      (Radiograph  by  Ueam,   of   Chicago.) 

radiograph.  Deep  shadows  would  be  cast  onto  the  film  or  plate  by  the 
subnitrate  of  bismuth,  showing  distinctly  the  course  of  the  fistula  and  the 
extent  of  the  abscess  cavity. 

The  curative  property  of  bismuth  paste  was  discovered  truly  by  acci- 
dent. After  using  the  paste  to  enable  him  to  make  better  radiographs, 
Dr.  Beck  noticed  that  some  bad  pus  cases  recovered. 

"Cargentos,"  a  colloidal  silver  oxid,  made  by  Mulford  &  Company, 
can  be  used  as  bismuth  paste  is  used,  for  either  radiographic  purposes  or 
as  a  remedy. 

When  the  use  "to  observe  the  course  of  a  fistulous  tract"  suggested 
itself  to  me.  T  had  in  mind  a  case  which  I  treated  some  years  ago.  It  was 
a  case  in  which  a  fistula  pointed  externally  at  the  symphysis.  Without 
going  into  a  detailed  history  of  the  case,  let  it  suffice  to  say  that  a  sound 
and  not  very  badly  impacted  lower  third  molar  was  finally  extracted  and 
the  case  recovered.  Probing  to  the  seat  of  the  trouble  was  impossible, 
but  had  the  fistula  been  injected  with  bismuth  paste  and  a  radiograph 
made,  the  connection  between  the  third  molar  and  the  fistulous  opening 
*Bi9muth   suhnitrate,  vaseline,  oaraflfine  and   white  wax. 


200 


DENTAL   RADIOGRAPHY 


at  the  symphysis  would  have  been  clearly  shown.  I  regret  that  I  have 
not  been  able  to  obtain  a  radiograph  of  such  a  case.  I  have  not,  however, 
and  must,  therefore,  content  myself  with  a  report  of  the  only  case  I  have 
in  which  bismuth  paste  was  used  to  trace  a  fistulous  tract. 

Case :  A  fistulous  opening  on  the  buccal  near 
Tigs.  211  and  212.  the  apex  of  an  upper  second  bicuspid ;  the  first  molar 
missing.  Another  fistulous  opening  on  the  buccal 
just  above  the  gingival  line  of  the  second  molar.  A  probe  entering  the 
fistula  above  the  bicuspid  led  to  its  apex.  A  probe  entering  the  fistula  of 
the  molar  seemed  to  lead  to  the  bifurcation  of  the  roots  of  the  molar. 
Having  at  a  previous  date  treated  the  molar,  and  so  knowing  the  condi- 
tion of  the  canals,  I  was  reluctant  to  believe  that  the  tooth  was  abscessed. 


Fig.   215 

Notice  the   considerable  canal  filling   forced  through  the   apical 
foramen.      (Radiograph   by  Blum,   of  New  York  City.) 
Same  case  as  Fig.  214.     After  apicoectomy.     (Radiograph  by  Blum,  of  New  York  City.) 


Fig.   214 
Fig.  214.     Before  apicoectomy. 

Fig.  215. 


I  entertained  the  belief  that  both  fistulous  openings  led  to  an  abscess  at 
the  apex  of  the  bicuspid,  but  I  could  not  verify  this  belief  by  probing.  A 
radiograph  (Fig.  211)  shows  the  canals  unfilled,  and  an  abscess  at  the 
apex  of  the  bicuspid.  It  shows  also  that  there  is  no  abscess  at  the  apex 
of  the  molar  roots.  But  it  does  not  show  a  fistula  leading  from  the  bi- 
cuspid to  the  molar.  The  shell-crown  on  the  bicuspid  was  removed  and 
phenolsulphonic  acid  pumped  through  the  tooth  and  out  of  the  fistula 
over  the  bicuspid,  but  the  acid  could  not  be  forced  through  the  bicuspid 
and  out  at  the  opening  over  the  molar.  The  tooth  and  both  fistulous 
openings  were  injected  with  bismuth  paste  and  a  radiograph  made.  (Fig. 
212.)  I  was  then  able  to  see  that,  as  I  had  suspected,  the  seat  of  the 
trouble  was  at  the  apex  of  the  bicuspid.  The  molar  did  not  need  treat- 
ment. The  phenolsulphonic  acid  could  not  be  forced  through  the  bicus- 
pid and  out  at  the  molar  fistulous  opening,  because  it  traveled  the  path  of 
least  resistance  out  the  nearer  opening.    The  fistulous  tract  could  not  be 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY     201 


seen  without  injection  with  bismuth  paste,  because  there  was  so  little 
bone  destruction.  Throughout  most  of  its  course  the  fistula  traveled  be- 
tween bone  and  periosteum. 

A  large  abscess  arising  at  the  apex  of  the  sec- 
fig.  213.  end  bicuspid,  and  discharging  above  the  artificial  first 
bicuspid.     Bismuth  paste  injected  into  tlie  fistulous 
tract.     Perhaps  the  cuspid  is  involved  also.     It  should  be  tested  for  vital- 
ity of  its  pulp. 


Fig.   216  Fig.   ill  Fig.   318 

Fig.    216.      The  apex    of   the   lateral   was   cut    off,    then   lost.      The    radiograph    shows   its    location, 

so  aiding  materially  in  its  removal.      (Radiograph  by  Ream,   of   Chicago.) 

Fig.  217.      A  chronic  abscess  at  the  apex  of  an  upper   central  incisor.     The  tooth   carries   a  post- 

poicelain  crown  and  the  canal  is  filled  almost  to  the  apex.      (Radiograph  by  Lewis,   of  Chicago.) 

Fig.    218.     The  same  as  Fig.   217  four  days   after  the  amputation   of   the   apex   of  the   central  and 

curettement  of   the  pus  sinus.        (Radiograph  by  Lewis,   of  Chicago.) 


30.   to  Obsert^e  tbe  field  of  Operation  Before  and  Jifter  Jlpicoectomy  (Root  imputation). 

When  a  tooth  fails  to  respond  to  less  radical 
Tigs,  214  and  215.  treatment,  and  it  is  deemed  necessary  to  amputate  a 
portion  of  the  apex  of  the  root,  the  question  nat- 
urally arises,  how  much  of  the  root  shall  be  cut  oiT?  A  good  radiograph 
will  answer  this  question.  Observe  that  a  great  amount  of  canal  filling 
penetrates  the  apical  foramen.  Fig.  215  is  of  the  same  case  illustrated 
in  Fig.  214  immediately  after  the  operation. 


In  his  work  on  Materia  Medica  and  Therapeu- 
fig.  216.  tics,  Dr.  Buckley  reports  an  interesting  case  of  apico- 

ectomy,  in  which  the  apex  was  amputated,  then  lost. 
A  radiograph  was  made.  (Fig.  216.)  Dr.  Buckley  says:  "This  radio- 
graph aided  materially,  as  it  verified  the  presence  of  the  root-end  and  its 
location." 


202 


^DENTAL  RADIOGRAPHY 


Radiographs  from  Dr.  Buckley's  Modern  Den- 
Tigs.  217  anfi  21$.       to,^  Materia  Medica,  Pharmacology  and  Therapeutics. 
They  are  exceptionally  good  pictures  taken  before 
and  after  amputation  of  the  apex. 

31.    to  Eocate  foreign  Bodies,  Sucb  as  a  Broach  in  the  Pulp  Canal  or  tissue  at  the 
Hpex  of  a  tootb;  H  Piece  of  lUooden  toothpick  in  the  Peridental  membrane,  etc. 

Case :    A  young  lady  about  twenty-five  years  of 

Tig.  219,  age.     Abscess  pointing  near  the  apex  of   an   upper 

central  incisor  carrying  a  post  porcelain  crown.     I 

suspected  that  the  canal  of  the  central  was  not  filled  properly,  and  made  a 


Fk 


219 


Fig.  221 


Fig.   219.      Cement  and  gutta-percha — mostly  cement — in   an   abscess   cavity  at  the  apex  of  a  post- 
porcelain    crowned    central    incisor. 
Fig.   220.      Same   as   Fig.   219,   after   what   was  thought   to  be   all   of   the   cement   and   gutta-percha 
was    removed.      The   radiograph    shows   both   some   cement    (the    larger    shadow)    and    some    gutta- 
percha   (the    small    shadow)    still    remaining    in    the    abscess    cavity. 
Fig.    221.      The    same   as    Fig.    219,    showing   the    abscess    cavity    clear    of    all    foreign    bodies. 


radiograph  (Fig.  219)  to  learn  if  in  this  surmise  I  was  correct.  The 
radiograph  shows  the  canal  filled.  At  the  apex  of  the  root  can  be  seen  a 
large  abscess  cavity,  with  foreign  bodies  of  some  nature  in  it. 

An  incision  was  made  on  the  labial  aspect,  and 

fig.  220.  what  was  thought  to  be  all  of  the  foreign  material. 

which  proved  to  be  cement  and  gutta-percha — mostly 

cement — was  removed  through  the  external  alveolar  plate.     A  radiograph 

(Fig.  220)  was  made,  and  shows  some  cement  (the  larger  shadow)  and 

some  gutta-percha  (the  small  shadow)  still  in  the  abscess  cavity. 

These  bodies  were  removed  and  another  radio- 
fig.  221.  graph  (Fig.  221)  made  to  prove  that  no  foreign  irri- 
tating body  remained  in  the  abscess  cavity. 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY    203 

The  pus  sinus  was  then  curetted,  washed,  cau- 
Tig.  222.  terized,    injected    with   bismuth    paste,    and   another 

radiograph  (Fig.  222)  made.  All  of  this  work  was 
(lone  at  one  sitting,  and  consumed  about  two  hours  time.  The  radiograph 
(Fig.  222)  shows  that  the  bismuth  paste  does  not  entirely  fill  the  abscess 
sinus.  It  has  been  my  experience  that  the  most  vigorous  and  earnest 
efforts  often  fail  to  "completely  fill"  an  abscess  cavity  with  bismuth  paste. 
The  manufacturers  of  the  paste  tell  us  that  "every  crevice"  must  be  filled 


Fis 


Fig.  r2.i 


Fig.    222.      Same   as   Fig.    219.      The    abscess    cavity    filled    with    bismuth    subnitrate    paste. 
Fig.    22.3.      Same    as    Fig.    219,    three    and    one-half    months    after    the    operation.       The    abscess 
cavity    is    entirely    filled    witli    new    bone.      The    new    bone    is    as    yet    not    quite    as    dense    as    the 

surrounding    bone. 


or  the  paste  will  not  have  the  desired  curative  effect.  Every  crevice  that 
can  be  filled  should  be,  I  concede.  But  I  am  showing  you  a  case  now  in 
which  the  sinus  was  not  quite  filled,  and,  as  we  shall  see  presently,  the 
results  obtained  were  ideal.  Three  days  after  the  operation  another  in- 
jection of  bismuth  paste  was  made.  At  this  sitting  the  paste  was  not  in- 
jected under  as  much  force  as  the  previous  injection,  for  I  did  not  wish 
to  break  up  and  destroy  any  granulation  tissue  that  had  formed  along  the 
walls  of  the  sinus.  Another  injection  under  even  less  pressure  than  the 
second  was  made  at  the  end  of  four  days.  The  patient  returned  one  week 
after  the  third  injection  with  no  symptoms  of  her  former  trouble. 

Three  and  one-half  months  after  the  operation 

fig,  223.  Fig.  223  was  made.     It  shows  a  most  remarkable  and 

gratifying  condition.     The  abscess  cavity  is  entirely 

filled  with  new  bone.     This  new  bone  is  as  yet  not  quite  as  dense  as  the 

surrounding  bone.  ^  ,^         r-jji  11       rr       11, 

*  Case  :     Man  of  middle  age  had  suffered  obscure 

fig.  224.  neuralgic   pams   for  about  a   month.      None   of   the 

teeth  on  the  affected  side  were  tender  to  percussion 


204  DENTAL  RADIOGRAPHY 

or  pressure.  A  radiograph  (Fig.  224)  was  made  to  learn  whether  or  not 
the  canals  of  the  upper  second  molar  were  filled.  There  was  a  very  large 
amalgam  filling  in  this  tooth.  The  radiograph  does  not  show  the  roots  of 
the  molar  well,  but  it  does  show  a  dark  shadow  between  the  second  and 
third  molars  just  above  the  cervical  margin  of  the  filling  in  the  distal  of 
the  second  molar.     On  inquiry  it  was  learned  that  the  patient  was  in  the 


Fig.  224  l"ig.  225 

Fig.    224.     The    arrow    points    into    a    piece    of    wooden    toothpick    between    the    second    and    third 

molars. 
Fig.   225.      The   upper  arrow   points   to   a   piece   of  broach   in  the  canal   of  the   upper   fiitt   bicuspid. 
The  lower  arrow  points  to  a  piece  of  gutta-percha  passing  through  a  perforation  to  the  distal. 

habit  of  using  wooden  toothpicks.  Suspecting  the  shadow  to  be  a  piece 
of  toothpick,  an  attempt  was  made  to  remove  it  with  explorers,  canal 
pluggers  and  silk  floss.  The  efifort  met  with  failure,  but,  feeling  sure  that 
my  diagnosis  was  correct,  the  third  molar  was  extracted.  The  piece  of 
toothpick  adhered  to  the  extracted  tooth.  There  was  an  immediate  and 
complete  recovery  from  pain.* 


*Immediately  after  Fig.  224  appeared  in  the  May,  1912,  issue  of  Items  of  In- 
terest, Dr.  C.  Edmund  Kells,  Jr.,  wrote  to  me  saying  there  must  be  some  mistake, 
that  wood  was  "absolutely  transparent"  to  the  X-rays,  and  that  according  to  the 
halftone,  Fig.  224,  the  piece  of  toothpick  cast  a  denser  shadow  than  the  amalgam 
filling  in  the  molar  tooth.  I  replied,  insisting  that  wood  was  not  "absolutely  trans- 
parent" to  X-rays,  explaining  that  it  had  been  necessary  to  retouch  the  print  to  make 
the  shadow  of  the  pick  show  at  all  in  the  halftone,  and  enclosing  the  original  nega- 
tive of  the  case.  I  then  received  two  disassociated  molar  teeth  stuck  together  side 
by  side,  with  pink  paraffin  and  wax,  and  a  piece  of  toothpick  in  the  wax,  parallel  to 
the  long  axis  of  the  teeth.  Also  a  radiographic  negative  of  the  teeth  and  a  letter 
from  Dr.  Kells,  saying  he  had  tried  to  make  a  radiograph  of  the  pick  and  had  failed. 
I  glanced  at  the  negative  and  could  see  only  the  teeth — neither  the  wax  nor  the  piece 
of  pick  between  them.  I  made  a  radiograph  of  the  test  specimen  Dr.  Kells  had  sent 
me  and  succeeded  in  showing  both  the  wax  and  that  part  of  the  ends  of  the  piece  of 
toothpick  which  extended  beyond  the  wax.  That  part  of  the  pick  covered  with 
paraffin  and  wax  could  not  be  seen. 

I  was  talking  of  the  experiment  and  showing  my  own  radiographs  to  a  dental 
student.  The  student  asked  to  see  Dr.  Kells'  negative,  he  examined  it  and  said, 
"Why,  I  can  see  the  same  thing  in  this  that  I  see  in  your  picture."  And  so  he 
could.  When  examined  closely  Dr.  Kells'  negative  showed  the  ends  of  the  piece  of 
toothpick  extending  beyond  the  wax.  I  had  not  examined  it  carefully  enough  before 
— neither  had  Dr.  Kells. 

I  appreciate  the  interest  Dr.  Kells  takes  in  my  work,  and  I  thank  him  most 
earnestly  for  calling  my  attention  to  what  seemed  to  be  a  mistake,  but  having  radio- 
graphed a  piece  of  toothpick  experimentally,  I  shall  not  retract  anything  said  re- 
garding Fig.  234. 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY     205 

Case :    Young  woman,  had  been  in  the  hands  of 
TIfl,  225.  an   incompetent  dentist,   who  had  treated  an  upper 

first  bicuspid  for  several  weeks,  and  had  finally  ad- 
vised its  extraction,  whereupon  the  patient  left  him,  presenting  to  me, 
and  asking  if  the  tooth  could  not  be  saved.  A  radiograph  (Fig.  225)  was 
made,  and  shows  a  piece  of  broach  in  the  canal  and  a  perforation  to  the 
distal  through  which  passes  a  gutta-percha  point.  About  the  end  of  the 
point  is  an  abscess.    Owing  to  the  position  of  the  tube,  which  was  placed 


Fig.  226  Fig.  227 

Fig.   226.      Unremoved  mesial   root  of   a  lower   second  molar. 

Fig.   227.      The   radiograph   proves   the   absence    of   an   unremoved    root   of   the   lower   first   molar. 

too  high,  the  teeth  in  the  picture  are  too  short,  and  the  perforation,  which 
was  well  above  the  gum  line — too  far  to  be  detected — seems  to  be  just  at 
the  neck  of  the  tooth. 

I  agreed  with  the  "incompetent  dentist"  that  the  tooth  could  not  be 
saved.  The  condition  revealed  by  the  radiograph  could  not  have  been 
learned  by  any  other  means  save  extraction  and  dissection  of  the  tooth. 

32.   to  Determine  tbe  Presence  or  Jibsence  of  a  Bit  of  Foot  Imbedded 
in  tbe  6um  tissue. 

After  the  extraction  of  a  great  number  of  teeth,  or  after  having  been 
operated  upon  by  some  other  dentist,  a  patient  will  present  with  the  gum 
tissue  highly  inflamed  and,  pointing  to  the  inflamed  area,  say,  "Isn't  there 
a  piece  of  tooth  there  yet?"  Unless  the  X-rays  are  used  it  is  necessary 
to  anesthetize  the  parts  and  dissect  away  some  of  the  soft  tissues  to  de- 
termine whether  the  inflammation  may  be  due  to  an  unremoved  bit  of 
tooth  root,  an  unresorbed  spicula  of  process,  or  a  bit  of  process  fractured 
from  the  jaw.  This  requires  a  great  deal  of  time  and  work,  and  causes 
the  patient  unnecessary  pain.     The  radiograph  should  be  used. 

Case :    Much  swelling  of  the  face  on  the  affected 

Tig.  226.  side.     The  patient  was  unable  to  open  the  mouth  to 

any  extent  without  considerable  pain.     Two  weeks 


2o6 


DENTAL  RADIOGRAPHY 


Fig.    328.      This    radiograph    is    of    a    di-y    subject.      Pictures    of    dry   bones    show    clearly    because 

there    are    no    soft    tissues    to    penetrate.       The    third    molar    is    badly    impacted    in    the    ramus. 

(Radiograph    by     Cryer,     of    Philadelphia.) 


previously  the  lower  second  molar  on  the  affected  side  had  been  extract- 
ed (?)  by  a  quack  dentist.  The  question  naturally  arose,  "Has  all  of  the 
second  molar  been  removed?"  A  radiograph  (Fig.  226)  was  made,  and 
shows  that  the  mesial  root  still  remains.  It  was  taken  out,  and  the  case 
recovered  promptly.  The  advantages  derived  from  using  the  radiograph 
in  this  case  were  as  follows:  It  saved  the  patient  the  pain  of  opening  the 
mouth  for  a  prolonged  instrumental  and  ocular  examination ;  and  also 
the  pain  caused  by  lancing,  dissecting,  and  probing  incident  to  such  an 
examination.  It  saved  both  the  patient  and  the  operator  time.  It  showed 
clearly  and  exactly  how  much  of  the  tooth  was  left,  and  illustrated  its 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY     207 

exact  location.     It  made   the  extraction  of  the  piece  of   root  decidedly 
easier  for  both  patient  and  operator. 

Fig.  227  is  of  a  case  similar  to  that  shown  in 
Ti9$.  227  mA  22§.  Fig-  226.  in  this  case,  however,  the  second  molar 
had  been  extracted  a  year  previously,  and  the  radio- 
graph shows  no  unremoved  bit  of  tooth  root.  The  radiograph  fails  to 
disclose  a  cause  for  the  clinical  signs.  But  let  me  impress  you  with  this 
fact :  it  does  show  that  an  unremoved  bit  of  tooth  root  is  not  the  cause, 
and  so  aids  us  very  greatly  in  a  diagnosis  by  elimination.    The  patient  did 


Fig.   229.      A.  piece  of  tooth   root   and   an   impacted   cuspid   in   an   otlierwise   edentulous   upper   jaw. 
(Radiograph    by    Lewis,    of    Chicago.) 

not  return  after  his  first  visit,  so  the  case  was  never  diagnosed.  There 
may  have  been  a  third  molar  impacted  in  the  ramus.  (See  Fig.  228.) 
No  one  can  deny  the  possibility.  We  took  only  the  first  step  toward  diag- 
nosis— we  eliminated  a  possible  cause. 

Though  I  have  been  unable  to  obtain  a  definite 

Tig.  229*  history  of  this  case,  it  is,  in  all  probability,  about  as 

follows :  After  the  extraction  of  the  upper  teeth  the 
patient  returned  with  a  localized  inflammation  of  the  gum  tissue  in  the 
cuspid  region.  A  radiograph  was  made  to  learn  if  this  inflammation  was 
caused  by  an  unresorbed  bit  of  process  or  a  piece  of  tooth  root.  The 
picture  shows  not  only  a  piece  of  tooth  root,  but  also  an  impacted  cuspid 
tooth.  It  is  not  unlikely  that  this  patient  suffered  from  obscure  neuralgic 
pains,  headache,  or  other  nerve  afifections. 

Notice  the  bit  of  root  imbedded  in  the  process. 

Tig.  230.  ^jy  chief  reason  for  exhibiting  this  picture  is  because 

it   shows    so    clearly   the   gum    tissue    overlying   the   process. 


208 


DENTAL  RADIOGRAPHY 


A  piece  of  root,  one  end  of  which  rests  on  the 

TI9.  23K  edge  of  an  ill-fitting  shell  crown,  the  other  against 

the  cuspid  tooth.     The  inflammation  caused  by  this 

root  extends  up  to  the  apex  and  to  the  mesial  of  the  cuspid.     In  such  a 

position  the  root  could  never  have  dropped  down  to  where  it  could  be 

seen  in  the  mouth. 


Fig.  230  Fig.  231 

Fig.   230.      The   arrow    points   to   a  bit   of   tooth   root.      Notice   how    clearly   the    gum    tissue    shows 

in   this   radiograph.      (Radiograph    by    Ream,    of    Chicago.) 

Fig.    231.      A   bit   of   tooth   root,    one    end   resting   on   the    edge   of   an    ill-fitting    shell    crown,    the 

other   against  the  cuspid.     The   abscess   caused   by   this   piece   of  root  extends  to   the   apex   and  to 

the  mesial  of  the  cuspid.      (Radiograph  by  Blum,  of  New  York  City.) 


33.    to  Diagnose  fracture  of  a  Root. 

Within  the  same  week  two  cases  in  which  the 
Tigs.  232  and  233.  upper  anterior  teeth  had  sustained  a  severe  blow  pre- 
sented at  the  college  clinic  for  treatment.  In  one  case 
a  lateral  incisor  (Fig.  232),  and  in  the  other  case  both  centrals  (Fig.  233) 
were  very  loose.  Radiograph  Fig.  232  shows  the  root  of  the  lateral 
fractured.  Extraction  is  indicated.  Radiograph  Fig.  233  shows  that 
the  roots  of  the  centrals  are  not  fractured.  Extraction  is  contraindicated, 
(As  can  be  seen  in  the  radiograph,  both  central  crowns  are  broken  ofif,  and 
one  lateral  is  knocked  out  completely.)  It  will  be  appreciated  that  the 
radiographic  findings  in  these  cases  governed  completely  our  course  of 
treatment.  I  would  suggest  it  as  a  most  rational  expedient  that  radio- 
graphs be  taken  in  all  cases  of  traumatism,  before  treatment  is  begun. 

Case :    Young  lady  fell  on  dance  hall  floor  strik- 
Tlfl.  234.  ing  the  upper  centrals  and  loosening  them.   Her  den- 

tist treated  both  teeth,  removing  inflamed  pulps.  One 
tooth  progressed  promptly  to  recovery,  but  the  other  remained  loose  and 
sore.  After  several  weeks  of  treatment  the  patient  presented  to  Dr.  F.  B. 
Moorehead,  of  Chicago,  who  had  a  radiograph  made  before  commencing 
treatment.     The  radiograph  shows  the  root  of  the  loose  tooth  fractured 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY    209 

near  the  apex.  Dr,  Moorehead  removed  the  apex  of  the  root  through  the 
external  alveolar  plate,  smoothed  the  end  of  the  broken  root,  and  the  case 
recovered  promptly.  It  is  almost  superfluous  to  do  so,  yet  I  want  to  call 
your  attention  to  the  fact  that  this  case,  like  very  many  others  I  have  re- 
ported, could  not  have  been  diagnosed  and  treated  properly  without  using 
the  radiograph. 


Fig.  233  Fig.  233  Fig.  334 

Fig.    233.      Fractured    upper    lateral    incisor.      Because    of    the    location    of    the    break    extraction 

is    indicated. 
Fig.  233.      It  was  thought  that  the   roots   of  the  centrals  were   fractured.      The  radiograph   shows 

they   are   not. 

Fig.  234.  Left  central  fractured  near  the  apex.  The  case  had  been  treated  for  alveolar  ab- 
scess without  success  for  several  weeks.  The  removal  of  the  piece  of  fractured  root-end 
through  the  external  alveolar  plate  effected  a  cure.     (Radiographed  by  Lewis,  of  Cliicago.) 


34.    to  Observe  tbe  Size  and  Sbape  of  Roots  of  Ceetb  to  be  Used  in  Crown 

and  Bridgework. 

Malformed     upper     laterals — "peg     laterals" — 
Tia.  235.  occur   quite    frequently.      Their   appearance   is   bad, 

and,  for  esthetic  reasons,  we  often  crown  them.  The 
porcelain  jacket  crown  is  difficult  to  construct  and,  at  best,  fragile.  If 
the  root  of  the  peg  lateral  is  long  enough  the  operator  may  elect  to  use 
a  post  porcelain  crown  of  some  kind  instead  of  the  porcelain  jacket. 
Fig-  235  shows  a  peg-shaped  lateral.  In  this  case  the  root  is  long  enough 
but  it  is  bent,  which  increases  the  risk  attending  devitalization  and  canal 
work. 


2IO 


DENTAL  RADIOGRAPHY 


Before    using    teeth    as    abutments    for    large 
Tig.  236.  bridges,  it  would  not  be  unwise  to  make  radiographs 

to  note  the  size  of  the  roots.  It  would  be  a  mistake, 
I  believe,  to  use  such  a  tooth  as  the  malformed  one  shown  in  Fig.  236  as 
an  abutment  for  a  bridge  of  any  extent.  It  should  be  borne  in  mind  that 
unless  the  pose  is  exactl}^  right — and  we  seldom  have  it  so — the  teeth,  as 
they  appear  on  the  radiograph,  do  not  represent  definitely  the  exact  length 
of  the  teeth  themselves.  Nevertheless,  the  radiograph  does  give  us  a 
fairly  definite  idea  of  the  relative  length  of  the  teeth. 


l-'ig.  rAh  Fig.  23() 

Fig.    235.      A  peg   lateral,    the   root   of    which    is   somewhat    tortuous.       (Radiograph    by    Blum, 

of    New    York    City.) 

Fig.    236.      A   malformed    cuspid   tooth.      It   would   be    a    mistake    to    use    such    a    tooth    as   an 

abutment    for    a    large    bridge. 


35.    Jf$  an  Jlid  and  Safeguard  Ulbcn  enlarging  Canals  for  Posts. 

There  are  times  while  enlarging  canals  for  posts  when  we  lose  the 
course  of  the  canal  and  are  much  disturbed  to  know  if  we  are  making  our 
enlargement  in  the  proper  direction.  Place  a  wire  in  the  canal  and  make 
a  radiograph.  If  the  enlargement  is  being  made  to  the  mesial  or  distal, 
with  danger  of  a  perforation,  this  can  be  seen  in  the  picture.  One  might 
completely  penetrate  the  side  of  the  root  towards  the  labial,  or  buccal,  or 
lingual,  without  being  warned  of  the  danger  by  a  radiograph,  but,  bear  in 
mind,  perforations  made  through  the  side  of  a  root  are  usually  either 
to  the  mesial  or  distal. 

In    Fig.    22,7,    observe    the    central    carrying    a 

Tig.  237.  post  porcelain  crown.     The  post  does  not  follow  the 

canal.     Had  the  enlargement  for  it  continued  in  the 

same  direction  as  was  started,  the  dentist  would  have  penetrated  the  side 

of  the  root.     A  radiograph  of  this  case  would  have  enabled  the  operator 

to  see  his  mistake  and  correct  it. 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY    211 

This  radiograph  shows  a  perforation  through  the 
Ti9.  23$.  side  of  the  root,  to  the  distal,  in  an  upper  second  bi- 

cuspid. The  perforation  was  made  when  enlarging 
the  canal  for  a  post.  A  probe  passes  through  the  side  of  the  root,  up  into 
an  abscess  cavity  at  the  apex  of  the  tooth. 

The  radiograph  is  an  aid  not  only  when  we  are  enlarging  canals  for 
posts,  but  also  when  we  are  removing  posts  from  canals.  It  shows  us 
how  long  the  post  is,  and  how  much  tissue  we  can  cut  away  from  the  sides 
of  it  in  safety. 


Fig.  237  Fig.  238 

Fig.   237.     The  post  in  the  post-porcelain   crowned   central   does   not    follow   the   canal.      It   almost 

penetrates   the    side    of    the   root.      (Radiograph    by    Graham,    of    Detroit.) 

Fig.    238.      Perforation    through    the    side    of    the    root    of    an    upper    second    bicuspid.      A    probe 

passes  through   the   perforation.      (Radiograph   by   Graham,    of   Detroit.) 

36.    to  examine  Bridges  JIbout  mbicb  tbere  T$  :Hn  Tnflammatiom 

At  best  fixed  bridges  are  not  sanitary.  For  this 
Tigs.  239  iintii  240.  reason  we  often  find  an  intense  inflammation  about 
them.  Thorough  depletion  by  scarifying  and  the  use 
of  an  astringent,  antiseptic  mouthwash  will  usually  give  prompt  relief. 
There  may  be  causes  for  the  inflammation  other  than  the  simple  fact  that 
the  bridge  is  a  foreign  body  in  the  mouth,  making  thorough  cleanliness 
impossible.  Observe  Figs.  129,  239  and  240  as  examples.  It  would  be 
extremely  difficult  to  remove  the  bit  of  root  shown  beneath  the  bridge  in 
Fig.  239  without  removing  the  bridge.  The  piece  of  root  shown  in  Fig. 
240  can  easily  be  removed  through  the  external  alveolar  plate  without 
removing  the  bridge.  Such  treatment,  however,  is  not  indicated  in  this 
particular  case. 

I  have  recently  heard  of  a  case  in  which  a  very  severe  inflammation 
existed  about  a  bridge  which  had  only  been  set  for  about  a  week.  The 
case  was  treated  for  several  days,  and  finally  the  bridge  removed  when  it 
was  seen  that,  at  the  time  the  bridge  was  set,  a  considerable  quantity  of 


212  DENTAL  RADIOGRAPHY 

cement  had  been  forced  into  the  tissues  near  a  shell  crown  abutment.  Re- 
moval of  this  cement  effected  a  prompt  cure.  Had  a  radiograph  been 
made,  the  cause  of  the  trouble  would  have  been  seen  immediately,  and, 
depending  on  the  exact  location  of  the  cement,  removal  of  the  bridge  may 
have  been  avoided. 


Fig.  239  Fig.  240 

Fig.    239.      A   piece   of   tooth    root   in   the   tissues   beneath    a   bridge.      (Radiograph    by    Lewis, 

of    Chicago.) 
Fig.   240.     A  piece  of  tooth  root   in   the  tissues  above    a    very    large    bridge.      (Radiograph    by 

Lewis,  of  Chicago.) 


37.    to  Observe  the  Tield  Before  Constructins  a  Bridge. 

This  use  of  the  radiograph  has  already  been  illustrated — Figs.  129, 
239,  and  240.  The  radiograph  will  not  only  disclose  the  presence  of  un- 
erupted  teeth,  and  unremoved  pieces  of  tooth  roots,  but,  as  has  been  sug- 
gested under  another  heading,  it  will  also  show  the  operator  the  size,  shape 
and  health  of  the  roots  of  the  teeth  he  is  using  for  abutments. 

3$.    Co  Observe  Planted  Ceetb. 

Case :  One  in  the  practice  of  Dr.  C.  Edmund 
TiflS.  241  and  242.  Kells,  Jr.,  Fig.  241,  shows  a  fracture  of  the  root  of 
a  lateral,  the  result  of  a  fall.  After  the  two  pieces 
of  the  lateral  were  extracted  they  were  united  and  held  together  with  an 
iridio-platinum  screw  set  in  cement,  and  the  repaired  root  then  replanted. 
The  radiograph  (Fig.  242)  was  made  immediately  after  the  operation.  A 
gold  splint  is  seen  covering  the  crown  of  the  cuspid,  lateral  and  both  cen- 
trals. 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY     213 

A  case  of  replantation  of  a  lower  second  bicus- 
Tla.  243.  pid  two  years  and  four  months  after  the  operation. 

The  root  is  almost  entirely  absorbed.  Notice  how 
plainly  the  pericemental  membrane  can  be  seen  about  the  roots  of  the  first 
bicuspid  and  first  molar,  appearing  as  a  light  line.  Notice  also  the  ab- 
sence of  this  line  about  the  remaining  portion  of  the  root  of  the  replanted 
tooth. 

The  theory  of  the  attachment  of  planted  teeth  is  as  follows:     The 
roots  of  the  planted  teeth  are  absorbed   at   different  points,   and  bone 


Fig.   241.  Fig.   242. 

Fig.    241.      Fracture   of  upper   lateral   incisor.      (Radiograph   by   Kells,    of   New    Orleans.) 

Fig.   242.      Same  as  Fig.    241   after  the  removal   of  the   lateral   and   its   replantation.    (Radiograph 

by  Kells,  of  New  Orleans.) 

immediately  fills  into  these  places,  so  holding  the  tooth.     Hence,  planted 

teeth  do  not  have  a  pericemental  membrane.     Radiographic  findings  bear 

out  this  theory.  -^.  .  .       ,          ,  ,  .  „, 

rig.  244  shows  an  implanted  porcelam  root.    Ub- 

Tifl.  244.  serve  that  the  root  has  practically  no  bony  attachment 

at  all,  and  would  drop  out  save  for  the  manner  in 
which  it  is  splinted  to  the  other  central. 

Dr.  E.  G.  Greenfield,  Wichita,  Kas.,  has  designed 
Tig.  24S.  and  manufactured  a  sort  of  cage-like  root  of  iridio- 

platinum  wire  to  be  used  for  implantation.  So  far 
all  forms  of  artificial  roots  for  teeth  have  proven  failures,  but  this  one 
bids  fair  to  be  a  success.  Whether  it  will  be  a  success  or  not  depends  on 
whether  or  not  bony  tissue  will  build  in  and  about  the  wires.  The  radio- 
graph (Fig.  245)  is  introduced  more  for  the  purpose  of  showing  the  arti- 
ficial roots  than  for  any  other  reason.  The  radiograph  has  not  been  made 
in  such  a  way  as  to  enable  us  to  see  whether  there  is  an  osseous  deposit 
within  the  wires  or  not. 


214 


DENTAL   RADIOGRAPHY 


39.    Tit  Cases  of  0cmentoma. 

Cementomata  (or  cases  of  hypercementosis,  as  they  are  often  called) 
are  sometimes  the  cause  of  neuralgia.  There  are  no  means  at  our  disposal 
whereby  they  (cementomata)  can  be  diagnosed  save  by  the  use  of  the 
radiograph. 


Fis 


243. 


Fig.   244. 


Fig.  343.  A  case  of  replantation  of  the  lower  second  bicuspid  two  years  and  four  months  after 
the  operation.  Tlae  root  is  almost  entirely  absorbed.  (Radiograph  by  Kells,  of  New  Orleans.) 
Fig.  244.     Artificial  porcelain  root  with  no  bony  attachment.     (Radiograph  by  Ream,  of  Chicago.) 


These  radiographs  illustrate  cementomata.     Ex- 
figs.  246  and  247.       traction  was  necessary  in  both  cases.     Experience  is  . 
teaching  me  that  when  hypercementosis  occurs  it  is 
usually  on  a  pulpless  tooth. 

40.   Tn  Cases  of  Bone  *'lUborIs." 

The  term  bone  whorl  is  used  to  designate  particularly  dense  areas  of 
bone  occurring  in  bone  Bone  whorls  may  be  caused  by  a  prolonged,  mild 
irritation,  like  that  produced  by  an  impacted  tooth,  for  example.  They 
are  sometimes  responsible  for  facial  neuralgia.  In  answer  to  a  letter  ask- 
ing him  if  he  ever  found  it  necessary,  or  ever  expected  to  find  it  necessary, 
to  open  into  the  bone  and  surgically  break  up  whorls  to  relieve  neuralgia. 
Dr.  Cryer  replies.  'T  have  found  it  necessary  in  several  cases  to  open  into 
the  bone  and  remove  the  whorls,  or  hard  bone,  and  I  fully  expect  to  do 
so  again."  From  the  nature  and  location  of  whorls,  it  is  obvious  that  they 
can  be  found  only  by  the  use  of  the  radiograph. 


THE   USES  OE  THE  RADIOGRAPH  IN  DENTISTRY   215 

Fig.    248    illustrates    the    radiographic    appear- 
Tig.  24$.  ance  of  a  bone  "  whorl." 

The  spot  indicated  by  the  arrows  has  the  ap- 

Tig.  249.  pearance  of  a  bone  "  whorl."     It  is  not,  however, 

it  is  a  piece  of  the  third  molar.     Under  a  general 

anesthetic  the  second  molar  was  removed  in  an  effort  to  extract  the  third 


Fig.    245.     Two   artificial  roots   implanted   in   the  upper  jaw.      (Radiographer   not   known.) 


Fig.  246.  Fig.   247. 

Fig.  246.      Cementoma  on  lower,  second,  shell-crowned  molar.   (Radiograph  by  Ream,  of   Chicago.) 
Fig.    247.     Cementoma.      (Radiograph  by   Ream,    of   Chicago.) 

molar.  Another  effort  was  made  to  remove  the  third  molar  when,  un- 
known to  the  operator,  a  piece  of  the  third  molar  was  broken  off  and 
dropped  in  the  alveolus  of  the  second  molar.  The  second  molar  was 
then  replanted. 

The  following  report  is  of  a  case  from  the  practice  of  Dr.  Cryer. 
The  patient  was  suffering  from  pain  on  one  side  of  the  face.  A  radio- 
graph of  the  affected  side  showed  an  impacted  third  molar.     Removal 


21 6 


DENTAL  RADIOGRAPHY 


"^ 


\ 


Fig.  24S.     The  arrows  point  to  a  bone  "  whorl." 


of  this  tooth  gave  rehef  for  about  ten  days  when  there  was  a  recurrence 
of  pain.  Another  radiograph  was  made  which  revealed  the  presence  of 
a  bone  "  whorl."  Another  operation  was  done  removing  the  "  whorl," 
after  which  neuralgia  disappeared  altogether. 


Case  in  the  practice  of  Dr.  Robert  H.  Ivy,  of 
Tifl.  250  Philadelphia.     "The  patient  had  suffered  from  neu- 

ralgia of  the  .mandibular  division  of  the  fifth  nerve 
on  the  right  side,  for  two  years.  In  February,  191 1,  she  was  treated  by 
an  alcohol  injection  of  this  division,  which  gave  relief  from  pain  for  six 
months,  after  which  the  trouble  returned,  but  not  so  severely  as  before. 
In  January,  191 2,  a  skiagram  was  made,  showing  a  dense  spot  in  the 


THE  USES  OE  THE  RADIOGRAPH  IN  DENTISTRY     217 

region  of  the  first  molar  tooth,  and  in  close  relation  to  the  inferior  dental 
nerve.  This  is  so  dense  as  to  appear  like  a  piece  of  tooth  root,  but  when 
cut  down  upon  with  the  surgical  engine,  nothing  but  dense  bone  was 
found.  The  patient  has  been  without  neuralgia  since  the  operation,  though 
it  is  too  soon  yet  to  say  whether  the  relief  will  be  permanent." 


41,    Co  Eocate  Stones  (Calculi)  in  tbc  Salivary  Dncts  or  Glands. 

The  history  of  this  case  given  me  by  Dr.  Sidney 

Tig.  2SU  Lange,  of  Cincinnati,  Ohio,  is  as  follows:  Patient, 

female,  age  about  forty,  suffered  recurrent  attacks  of 

swelling  and  pain  in  the  region  of  the  submaxillary  gland  on  one  side. 


Fig.   249.      The  arrows  point  to  a  spot  having  the  appearance   of  a  bone  "  whorl."      It   is   not  a 

bone    "  whorl,"    however. 


The  attacks  seemed  to  follow  the  taking  of  sour  foods.  A  radiograph 
(Fig.  251)  was  made.  The  arrow  points  to  a  stone  in  the  submaxillary 
duct.  Because  the  patient  had  had  a  stone  removed  from  the  same  duct 
several  years  previously,  and  because  the  gland  was  considerably  thick- 
ened, simple  removal  of  the  stone  was  thought  to  be  contraindicated,  and 
a  more  radical  operation  involving  the  removal  of  the  entire  gland  was 
performed. 


2l8 


DENTAL  RADIOGRAPHY 


42.   Tn  €a$c$  of  Bone  Cysts. 

"A  cyst  is  an  organized  structure  consisting  of  a  sac-like  wall  to- 
gether with  its  contents,  especially  one  of  pathological  formation  or 
abnormal  development." — Appleton's  Medical  Dictionary. 


Fig.    250.      The    dark    shadow    to    which   the   arrow   points   is    a    bone    "whorl." 

Pancoast,    of    Philadelphia.) 


(Radiograph    by 


According  to  this  definition  all  chronic  alveolar  abscesses  are  cysts — 
bone  cysts,  because  they  occur  in  bone.  But  the  name  cyst  is  usually  not 
applied  until  the  abscess  sac  assumes  a  great  size.  The  abscess  in  Fig. 
193  is  large  enough  to  be  called  a  cyst,  in  the  generally  used  sense  of  the 
term. 

This  radiograph  shows  a  large  cyst  in  the  lower 

fifl.  252.  jav/.     The  two  roots  of  the  lower  first  molar  are 

doubtless  responsible  for  the  cyst  formation. 

In  cyst  cases  there  is  often  considerable  and  disfiguring  enlargement 

of  the  bone,  and  such  cases  are  spoken  of  as  cystic  tumors,  a  tumor,  of 

course,  being  simply  an  abnormal  enlargement  or  growth. 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY     219 

A  man,  age  about  thirty-seven,  was  referred  to 

fig.   253  the  college  clinic  "to  have  a  growth  on  the  lower  jaw 

cut  off."    There  was  no  "growth"  to  "cut  off."   There 

ivas  a  definite  enlargement  of  the  bone  in  the  lower  first  molar  region, 


Fig.    251.     The    arrow    points    to    a    stone   in    the    submaxillary    duct.       (Radiograph    by    Lange,    of 

Cincinnati.) 


giving  the  man  the  appearance  of  carrying  a  large  lump  of  tobacco 
in  the  vestibule  of  the  mouth.  The  patient  suffered  local  pain,  and  the 
involved  area  was  tender  to  palpation.  The  first  molar  tooth  was  missing 
from  the  jaw.  A  radiograph  was  made  and  showed  a  cyst  involving  the 
second  bicuspid  and  second  molar.  (I  regret  that  the  radiograph  has  been 
lost.)  Neither  the  second  bicuspid  nor  the  second  molar  had  cavities  nor 
fillings  in  them.  Considering  the  evidence  of  neglect  of  the  mouth  and 
teeth,  it  was  not  deemed  worth  while  to  try  to  conserve  the  teeth.  Ac- 
cordingly the  second  bicuspid  was  extracted,  which  permitted  the  escape 
of  considerable  watery,  brown  pus.  A  doubt  then  arose  as  to  whether 
the  radiograph  showed  an  involvement  of  the  molar  or  not.  Another 
radiograph  (Fig.  253)  was  made.  It  shows  that  the  molar  is  involved. 
It  was  extracted  and  more  serous  pus  evacuated.     Antiseptic  solutions 


220 


DENTAL   RADIOGRAPHY 


could  now  be  washed  from  one  tooth  socket,  through  the  cyst,  and  out  at 
the  other  tooth  socket.  The  cyst  was  curetted,  cauterized  and  packed  with 
sterile  gauze.  Healing  except  from  within  outward  was  prevented  by  the 
use  of  gauze,  and  the  case  recovered.    Relief  from  pain  and  soreness  was 


Fig.    252.      Large   cyst   in   the    lower    jaw.      The    more    or    less    oval-shaped    light    area    represents 
the  cyst.      (Radiograph  by  Lewis,  of  Chicago.) 


Fig.  253. 


Fig.  254. 


Fig.  253.     Cyst  in  lower  jaw.     The  circle  A  is  the  alveolus  from  which  the  second  bicuspid  was 
extracted.     Fig.  254.     Cyst  in  upper  jaw,  in  apical  region  of  pulpless  upper  first  molar.      Enlarge- 
ment, as  seen  in  mouth  above  first  molar,  about  the  size  and  shape  of  one-half  hazelnut. 


Immediate.     It  required  two  or  three  months  for  all  of  the  enlargement 
of  the  jaw  to  disappear. 

In  my  experience  as  a  radiographer  I  have  observed  that  the  general 
practitioner  of  dentistry  shows  great  reluctance  to  extract  a  tooth,  no 
matter  what  the  condition  he  is  treating  may  be.     On  the  other  hand,  the 


THE  USES  OE  THE  RADIOGRAPH  IN  DENTISTRY     221 

specialist  in  oral  surgery  extracts  teeth  sometimes  without  making  the 
slightest  effort  to  conserve  them.  I  believe,  however,  that  the  oral  surgeon 
is  less  often  mistaken.  A  man  may  make  a  greater  mistake  than  the  ex- 
traction of  a  tooth.  For  example :  failure  to  extract  a  tooth  which  is 
causing  otherwise  incurable  suppuration,  general  sepsis,  nervous  dis- 
orders, necrosis  or  distracting  pain. 


Fig.   355.     A  very  large   cyst  of  the  lower  jaw.      The   light  area  represents  the   cyst.      This  radio- 
graph  shows    the   hyoid   bone.    (Radiograph   by   Lange,   of    Cincinnati.) 

Dr.  Sidney  Lange,  of  Cincinnati,  made  the  radio- 
TJg.  255.  graph  shown  in  Fig.  255,  but  did  not  treat  the  case. 

Dr.  Lange  was,  however,  able  to  furnish  the  follow- 
ing history :  Patient,  boy,  about  eighteen.  Very  large  swelling  in  the 
lower  jaw.  No  pain  or  tenderness  in  the  region  of  enlargement.  A  radio- 
graph (Fig.  255)  was  made,  and  the  case  diagnosed  as  a  "benign  bone 
cyst."    The  boy  was  taken  to  a  hospital  and  the  cyst  drained  of  a  straw- 


222 


DENTAL  RADIOGRAPHY 


colored  fluid,  curetted  and  packed  with  gauze,  through  an  opening  made 
inside  of  the  mouth  to  the  buccal.  The  patient  left  the  hospital  in  a  week 
or  two  after  the  operation. 

Case :     Male,  age  about  twenty-five.     Enlarge- 

Tifl.  256.  ment  of  the  mandible  at  the  symphysis.     Tenderness, 

intermittent  local   pains.      The   radiograph   shows   a 

large  cyst.     Failing  to  keep  an  appointment,   the  patient  has  not  been 

heard  of  since  the  radiograph  was  made. 


Fig.    356.     Bone    cyst    of    the    lower    jaw. 


43.   Tn  Cases  of  Dentigcrous  Cyst. 

Any  cyst  containing  a  tooth  body,  or  tooth  bodies,  is  said  to  be  a 
dentigerous  cyst.  Dentigerous  cyst  of  the  jaws  are  not  uncommon.  Their 
definite  diagnosis  is  possible  only  when  the  radiograph  is  used. 

Because  the  apex  of  the  toOth  extends  into  the  pus  sac  a  chronic 
dento-alveolar  abscess  is  sometimes  called  a  dentigerous  cyst.  But  this 
use  of  the  term  is  considered  improper. 

Case  in  the  practice  of  Dr.  M.  H.  Cryer.    I  quote 

Tig.  257.  Dr.    Cryer :      "The   patient,   a   child  of  nine,   had  a 

swelling  of  the  left  side  of  jaw  for  about  two  years. 

This  gradually  increased  to  the  size  of  a  hen's  egg,  causing  considerable 

deformity.     A  radiograph  of  the  case   (Fig.  257)   shows  a  retained  de- 


THE  USES  OE  THE  RADIOGRAPH  IN  DENTISTRY     223 


Fig.   257.      Dentigerous  cyst   of  the   lower  jaw   in  child  nine  years   old.      The  arrow   points   to   the 
tooth  in  the  cyst.   The  light  area  represents  the   cyst.    (Radiograph  by  Pancoast,   of  Philadelphia.) 


ciduous  second  molar  tooth  at  the  lower  border  of  the  jaw  and  surrounded 
b_y  an  ovoid  clear  area.    A  diagnosis  of  dentigerous  cyst  was  made. 

"At  operation  through  the  mouth  the  shell  of  bone  was  found  to  con- 
taiii,  not  the  usual  fluid,  but  a  resilient  mass  of  pinkish-white  tissue  sur- 
rounded by  a  sac  of  darker  color.  The  contents,  including  the  soft  tissues, 
the  tooth  shown  in  the  picture  and  the  sac,  were  removed  and  the  cavity 
lightly  packed  with  gauze.  The  patient  is  making  an  uneventful  recovery. 
The  further  diagnosis  of  the  case  will  depend  on  microscopic  examination 
of  the  tissue." 

Fig.-  258  was  made  for  a  patient  of  Dr.  J.  G. 
Tigs.  25$  and  259.       Lane,  of  Philadelphia.     Age  of  patient,  eight.     The 
radiograph  shows  an  unerupted  second  bicuspid  sur- 
rounded by  a  light  area  representing  a  dentigerous  cyst.     The  upper  wall 


224 


DENTAL   RADIOGRAPHY 


Fig. 


258.      A   dentigerous   cyst   containing   a   lower    second   bicuspid. 

of    Philadelphia.) 


(Radiograph   by   Pancoast, 


of  the  cyst  and  its  fluid  contents  were  removed,  leaving  the  tooth  in  place. 
xA.  later  radiograph  (Fig.  259)  shows  that  the  tooth  is  gradually  erupting 
into  position.     (This  history  is  quoted  from  a  paper  by  Dr.  Cryer.) 

44.   Tn  0a$e$  of  tumor.  Benign  or  malignant. 

I  have  already  reported  a  case  of  cystic  tumor,  which  was  referred 
to  the  college  clinic  to  have  the  tumor  "cut  oflf."  There  was  nothing  to 
"cut  off,"  and  a  radiograph  showed  a  cavity  in  the  bone,  aspiration  of 
which  accomplished  a  cure. 

The  following  cases  occurred  in  the  practice  of 

Tig.  260,  Dr.  Cryer :    "The  two  patients  were  sent  by  different 

practitioners  from  different  portions  of  the  State  of 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY     225 


Fig.    359.      Same   as   Fig.    258    after    removal    of    the    fluid    contents    and    upper    wall    of    the    cyst, 
showing  the  second   bicuspid    erupting  into  place.      (Radiograph   by   Pancoast,   of   Philadelphia.) 


Pennsylvania,  but  came  for  examination  on  the  same  day.  They  were 
two  women  patients  of  about  the  same  age,  both  wearing  full  upper  arti- 
ficial dentures  and  partial  lower  ones,  and  both  suffering  from  a  similar 
character  of  pain,  the  only  difference  being  that  in  one  patient  the  pain 
was  located  on  the  left  side  of  the  lower  jaw,  while  the  other  was  on  the 
right  side  of  the  lower  jaw.  Physical  examination  revealed  the  fact  that 
the  right  cervical  lymphatic  glands  in  one  of  the  patients  were  slightly 
enlarged.  The  history  obtained  of  the  cases  did  not  aid  in  diagnosis. 
Both  patients  claimed  that  the  molar  teeth  on  each  side  had  been  ex- 
tracted years  ago.  X-rays  were  made  of  the  jaws  with  the  following 
results : 

"Fig.  260  was  made  from  the  patient  whose  cervical  glands  were 


226 


DENTAL  RADIOGRAPHY 


Fig. 


260.     Myelosarcoma   of   the   lower   jaw.      In   appearance   it   resembles   a   bone   cyst   somewhat. 
(Radiograph   by    Pancoast,    of    Philadelphia.) 


enlarged.  The  picture  shows  a  breaking  down  of  the  bone,  with  the  two 
dark  shadows  indicating  abnormal  density  of  the  bone  in  some  portions. 
From  this  appearance,  together  with  the  shght  enlargement  of  the  glands, 
the  case  was  diagnosed  as  myelosarcoma.  A  microscopic  examination  of 
the  tissue  removed,  confirmed  the  diagnosis." 

I  do  not  reproduce  the  radiograph  of  the  other  case  because  the  print 
I  have  is  not  clear  enough  to  permit  of  a  good  halftone  reproduction.  The 
print  before  rae  shows  fairly  well  three  impacted  lower  teeth,  one  a  rudi- 
mentary bicuspid,  the  others  a  second  and  third  molar. 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY     227 

Dr.  Cryer  says :  "There  seemed  to  be  very  little  difference  in  these 
two  cases  from  the  history  and  physical  examination,  but  the  wonderful 
work  of  the  X-rays  revealed  a  very  great  dissimilarity.  On  the  one  hand 
the  skiagraph  indicated  the  sad  necessity  of  removing  the  entire  right  side 
of  the  jaw  and  submaxillary  lymphatic  glands,  with  the  possibility  of  the 
disease  returning,  while  in  the  other  case  the  extraction  of  the  three  im- 
pacted teeth  was  the  only  thing  required." 


Fig.   261.  Fig.   263. 

Fig.  361.     Osteoma   (?)   of  the  lower  jaw. 
Fig.    262.      Hypertrophy    of   the    gums    and   alveolar    process.      The    radiograph    shows    no    irritant 
cause   for   the   condition,    and   none   was   found    otherwise. 


My  readers  are  by  this  time  acc[uainted  with  the 

Tifl.  261.  appearance  of  normal  alveolar  process  and  jaw  bone. 

Fig.  261   shows  what   I  believe  to  be  an   osteoma. 

The  patient  would  not  consent  to  the  removal  of  tissue  for  microscopical 

examination.    The  radiograph  shows  only  that  the  bone  is  diseased.    The 

exact  nature  of  the  disease  must  be  determined  by  the  microscope. 

Case :    Enlargement  of  the  gums  about  the  upper 
Tifl.  262.  anterior    teeth,    causing    considerable    disfigurement. 

Fig.  262  shows  what  was  thought  to  be  hyper- 
trophy of  the  gum  tissue  and  alveolar  tissue.  Microscopic  examination 
verified  the  diagnosis.  The  teeth  and  the  hypertrophied  tissue  were  re- 
moved. 

At  the  age  of  thirteen  a  permanent  lateral  had 

Tifl.  263.  failed  to  erupt.     A   radiograph   was  made  to  learn 

whether  or  not  it  was  present  in  the  jaw.     Fig.  263 

shows  the  permanent  lateral,  and  shows  also  why  it  has  not  erupted.     In 


228  DENTAL  RADIOGRAPHY 

the  path  of  eruption  is  seen   what  I  beheve  to  be  an  "epithelial,  com- 
posite"* odontoma. 

Oflontomata  sometimes  assume  considerable  size.  To  be  abso- 
lutely sure  in  diagnosis,  and  to  be  certain  of  their  complete  removal,  the 
radiograph  should  be  used. 


Fig.    263.      The   upper   arrow   points    to    the    permanent   lateral    incisor.      The    lower    arrow    points 
to   an    odontoma.      (Radiograph    by   Flint,    of   Pittsburgh.) 


"The    case    illustrated    in    Fig.    264    presents 
TI9.  264.  many   interesting   features    from   the    standpoint   of 

diagnosis  and  treatment.  The  patient  was  a  woman 
about  thirty-five  years  of  age,  who  suffered  for  a  number  of  years  from 
pains  in  the  ear  and  the  tonsilar  region,  as  well  as  from  difficulty  in  masti- 
cation and  deglutition,  while  her  general  health  had  deteriorated  to  such 
an  extent  that  she  became  very  anemic,  having  suffered  from  malnutrition 
due,  no  doubt,  to  imperfect  mastication  and  the  absorption  of  pus  prod- 
ucts. In  this  condition  she  was  referred  to  the  extracting  specialist  who 
was  unable,  from  the  ankylosis  present,  to  arrive  at  any  definite  conclusion 
as  to  the  possibility  of  an  impacted  tooth  which  was  suspected,  while  the 
only  evidence  that  pointed  in  this  direction  was  a  free  discharge  of  pus 
through  a  fistulous  opening  in  the  soft  tissues  over  the  third  molar  region 
'of  the  right  inferior  maxillary. 

"She  was  therefore  referred  to  the  radiographer  when  the  true  con- 
dition, as  shown  in  Fig.  264,  was  revealed.  The  necessity  for  removing 
the  displaced  second  molar,  as  well  as  the  odontoma,  presented  a  situation 
which  was  not  a  pleasing  one  to  contemplate.  The  patient,  as  well  as  her 
friends,  were  informed  of  the  probability  of  fracturing  the  mandible  in 
the  endeavor  to  remove  the  molar  and  the  dental  tumor,  which  together 


*Barrett  "Oral   Pathology   and    Practice." 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY    229 


Fig.    264.     A    large    composite    odontoma.       (Radiograph    by    Chene,    of    Detroit.) 


occupied  almost  the  entire  body  of  the  mandible  at  the  angle  of  the 
ramus.  Under  a  general  anesthetic  of  nitrous  oxide  and  oxygen,  which  was 
followed  by  ether,  the  tumor  was  removed,  as  was  also  the  impacted  molar, 
without  any  great  difficulty,  but  when  the  circumscribed  bony  structure 
about  the  molar  was  drilled  and  chiseled  sufficiently  to  permit  of  an  ele- 
vator passing  under  one  corner  of  it  and  pressure  applied,  the  expected 
happened,  and  a  break  in  the  body  of  the  mandible  occurred.  This  acci- 
dent was  of  no  serious  consequence,  however,  for  under  an  occipito- 
mental bandage,  which  a  few  days  later  was  reinforced  by  wire  fixation, 
the  fracture  healed  and  the  case  proceeded  to  an  uneventful  and  speedy 
recovery,  with  complete  restoration  of  health.  The  odontoma  was  of 
composite  structure,  the  central  part  being  made  up  of  what  may  have 
been  the  third  molar,  about  which  were  arranged  concentric  layers  of 
cementum,  and  probably  some  compact  bony  structures." 

For  the  report  of  this  case  I  am  indebted  to  Dr.  Don  M.  Graham,  of 
Detroit,  Mich, 


230  DENTAL  RADIOGRAPHY 

45.    to  Observe  Anomalous  Conditions  Sucb  as  the  Tusion  of  the  Roots  of 
two  Ccetb  for  example. 

Case :  Child  about  twelve.  The  crowns  of  two  of 
Tig.  265.  the   lower  incisors  seemed   fused  together.     To  ac- 

complish regulation  of  the  teeth  it  became  expedient 
in  the  opinion  of  the  operator  handling  the  case  to  extract  one  of  the 


Fig.   265.      Shows   that   the   two   lower   incisors    are    not    fused   together. 

incisors.  The  choice  of  the  tooth  to  extract  fell  to  one  of  the  two  which 
seemed  fused  together.  The  question  arose :  "Are  the  roots  of  the  teeth 
fused  also?"  A  radiograph  (Fig.  265)  shows  they  are  not.  It  shows 
further  that  the  crowns  are  not  fused  either,  though,  let  me  admit,  I 
shared  in  the  mistake  of  the  man  who  referred  the  case  thinking  they 
were ;  and  failed,  as  he  had,  in  an  attempt  to  pass  a  ligature  between 
them.  It  was  not  until  I  had  the  radiograph  before  me,  showing  me  that 
I  was  not  attempting  the  impossible,  that  I  succeeded  in  getting  a  silk 
ligature  between  the  teeth.  One  of  the  teeth  was  slightly  malformed  ; 
they  were  almost  mortised  together  in  consequence,  and  in  contact  from 
the  incisal  edge  to  beneath  the  gum  margin. 

Second  and  third  molars  are  sometimes  fused  together.  I  recall  hav- 
ing extracted  the  upper  second  and  third  molars  in  an  efifort  to  remove 
the  third,  the  roots  of  the  two  teeth  having  been  coalesced.  Had  I  used 
radiographs,  and  known  the  condition  which  existed,  I  might  have  con- 
served the  third  molar,  and  so  saved  the  second  molar,  which  latter  was 
a  useful  tooth.  Or,  had  it  been  necessary  to  remove  the  teeth,  I  might 
have  saved  my  patient  considerable  pain  by  a  more  inclusive  use  of  my 
local  anesthetic. 


THE  USES  OE  THE  RADIOGRAPH  IN  DENTISTRY    231 

46.   to  Observe  tbc  Cocation  ana  extent  of  a  necrotic  or  Carious  CoHdition 

of  Bone. 

This  radiograph  is  of  a  case  of  arsenical  necrosis, 

Ti9.  266.  which    would    not   yield   to   the   usual   treatment    of 

curettement  and  drug  stimulation.    The  arrow  points 

to  the  line  of  demarcation,  below  which  can  be  seen  the  sequestrum.-    Tii€ 

case  recovered  promptly  upon  removal  of  the  sequestrum. 


Fig.   266.     The  arrow  points  to  the  line  of  demarcation,   beneath   which  can   be   seen   the 

sequestrum. 


Case:  Necrosis  of  the  lower  jaw,  caused  by  an 
TiflS.  267  and  26$.  abscessed  tooth.  The  patient  sufifered  for  a  year 
from  recurrence  of  an  abscess  in  the  lower  jaw.  Dur- 
ing this  time  he  made  several  changes  from  one  dentist  or  physician  to 
another.  At  the  time  the  case  came  under  the  care  of  Dr.  Gilmer,  of 
Chicago,  the  symptoms  were  alarming.  There  were  two  external  pus 
sinuses  along  the  lower  border  of  the  mandible  in  the  bicuspid  region. 
The  patient  had  been  unable  to  lie  down  for  a  period  of  ten  days  because 
of  the  intense  pain  which  resulted  from  assuming  a  recumbent  position. 
The  body  temperature  rose  and  fell  by  turns.     Stupor  and  coma  occurred. 

A  radiograph  of  the  case  (Fig.  267)  shows  a  sequestrum  about  the 
size  of  the  first  joint  of  the  thumb  along  the  lower  border  of  the  mandible 
in  the  bicuspid  and  cuspid  region.  The  line  of  demarcation  can  be  seen 
fairly  well  in  the  plate  before  me.  I  regret  that  I  was  unable  to  obtain  a 
good  print  of  this  case.  The  negative  was  an  excellent  one,  but  the 
photographer  who  made  the  print  from  it  did  poor  work. 

The  operation,  done  by  Dr.  Gilmer,  of  Chicago,  was  as  follows :  An 
external  incision  was  made  along  the  lower  border  of  the  mandible  in  the 
region  of  the  sequestrum,  and  the  sequestrum  removed  through  it.  The 
bone  was  curetted,  a  drainage  tube  inserted,  and  the  incision  sewed  up. 
The  first  bicuspid  and  cuspid  were  extracted. 


232 


DENTAL  RADIOGRAPHY 


Fig.    267.      The    arrow    points   to    a    sequestrum    about    the    size    of    the    first    joint    of    the    thumi) 
(Radiograph   by   Porter,   of   Chicago.) 


Fig.    368.     Same   as   Fig.    S67,    with   the   line    of    demarcation   outlined    to    enable    the    reader    to 
observe  it  better  than  in   Fig.   267. 


THE  USES  OE  THE  RADIOGRAPH  IN  DENTISTRY     233 


Fig.    269.      EE,    ends   of   overlapping   bone. 


Had  the  operator  not  had  a  radiograph  to  guide  him  in  his  work  he 
could  not  possibly  have  performed  the  operation  as  quickly,  thoroughly, 
and  intelligently  as  he  did,  for  he  would  not  have  known  just  where,  and 
just  how  big,  the  sequestrum  was. 

A  case  of  phosphor  necrosis  of  the  lower  jaw 
Tifl.  269.  several  years  after  removal  of  the  sequestrum.     The 

jaw  is  in  two  parts,  with  the  ends  overlapping. 

A  carious  condition  of  the  alveolar  process  and 

Tifl.  270.  superior  maxillary  bone,  caused  by  the  retention  of  a 

piece  of  tooth  root  above  the  dummies  of  a  bridge. 


234  DENTAL   RADIOGRAPHY 

47.    to  Diagnose  Hntral  6nipyeni(i. 

This  radiograph  was  made  from  a  dry  skull.    It 
fffl.  271.  shows  the  f oHowing :     The  frontal  sinuses  AA,  the 

orbits  BB,  ethmoid  cells  CC,  the  nasal  cavity  DD, 
and  the  maxillary  sinuses  EF.  The  sinus  E  is  filled  with  lead  shot,  the 
sinus  F  has  a  molar  tooth  in  it.  The  picture  is  printed  to  give  one  an 
opportunity  to  study  the  "landmarks"  of  such  a  radiograph,  and  so  enable 
one  to  interpret  the  coming  pictures  more  readily. 


Fig.    270.     Carious    condition    of    the    alveolar    process    and    bone,    caused    by    a    piece    of    tooth 
root    above    the    dummies    of    a    bridge.       (Radiograph    by    Lewis.) 

To  observe  pus  in  the  antrum  it  is  necessary  to 
Tig.  272.  make  a  radiograph  of  both  antra,  that  they  may  be 

compared.  In  Fig.  272  the  antrum  A  is  filled  with 
pus,  the  antrum  B  is  healthy.  It  must  be  borne  in  mind  that  the  radio- 
graph alone  does  not  demonstrate  to  us  the  presence  of  pus  in  the  antrum. 
It  shows  us  only  that  there  is  something  in  the  antrum.  The  appearance 
of  the  radiograph  would  be  about  the  same,  whether  that  something  were 
pus  or  a  soft,  tumorous  growth.  Such  a  radiograph  as  Fig.  272  will  show 
whether  the  disease  is  confined  to  the  antrum  or  involves  the  ethmoidal 
cells  and  frontal  sinuses.    In  this  case  the  disease  exists  only  in  the  antrum. 

Cloudiness  of  the  antrum  A  indicates  a  patho- 

TfgS.  273  and  274.       logical    condition.      In    Fig.    273    the    arrows    point 

to  a  dark  shadow,  which  is  an  impacted  upper  third 

molar  tooth.     Fig.  274  is  a  lateral  view  of  the  same  case,  and  shows  the 

impacted  tooth  clearly.     Extraction  of  the  tooth  effected  an  immediate 

cure.     (This  case  was  one  in  the  practice  of  Dr.  Cryer.) 

4$.   to  Observe  the  Size,  Shape  and  Location  of  the  Jintrum,  as  an  JTid  in 

Opening  into  Tt. 

Unless  a  pus-filled  antrum  is  opened  at  its  low- 
Tig.  275.  est   point,    it   cannot   be   perfectly    drained.      Unless 
it   is   perfectly   drained   the   operation   cannot   result 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY     235 


Fig.    271.      Radiograph    of    a    dry    skull.      One    antrum    is    filled    with    lead    shot,    the    other    has 
a    molar    tooth    in    it.      This    radiograph    is    clearer    than    one    made    from    the    living    subject    be- 
cause there  were  no  soft  parts   or  circulating  blood  to   blot  out    detail. 


in  a  permanent  cure.  The  size,  shape  and  location  of  the  antrum  can 
best  be  observed  stereoptically.  Often,  however,  a  good  idea  of  its  size, 
shape  and  location  can  be  obtained  from  a  radiograph,  like  Fig.  276, 
for  example.    Radiographs  of  the  antrum  made  on  films  held  in  the  mouth 


236 


DENTAL   RADIOGRAPHY 


Fig.    272.     A,    antrum    with    pus    in    it. 


B,    healthy    antrum. 
Louis.) 


(Radiograph    by    Carman,    of    St. 


are  very  misleading  and  confusing,  as  witnessed  in  Fig.  275,  which  was 
made  on  a  film  held  in  the  mouth,  and  is  of  the  antrum  filled  with  lead 
shot — illustrated  in  Fig.  271. 

The  dots  outline  a  very  large  antrum.    An  open- 
Tffl.  276.  ing  made  at  the   favorite  site  for  opening  into  the 

antrum  through  the  mouth,  above  their  apices,  be- 
4;ween  the  second  bicuspid  and  first  molar  (the  first  molar  has  been  ex- 
tracted), would  not  puncture  this  antrum  at  its  lowest  point.  The  root 
of  the  second  molar  seems  to  penetrate  the  antrum.  Whether  it  actually 
penetrates  the  floor  of  the  antrum  or  not  I  cannot  say  definitely,  because 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY    237 


Fig.    273.      A,    diseased    antrum.      The    shadow    pointed    to    by    the    arrows    is    an    impacted    third 
molar.      B,   healthy  antrum,   CC,   turbinate  bones,   EE,  very   small   frontal   sinuses.      (Radiograph 

by   Pfahler   of   Philadelphia.) 


of  the  lack  of  perspective  in  the  radiograph.  I  am  inchned  to  think,  how- 
ever, that  it  does  not — the  lower  part  of  the  antrum  and  the  end  of  the 
root  overlap,  the  tooth  root  passing  to  the  lingual  of  the  antrum. 

Because  of  its  unusual  size  the  lower  part  of  the  antrum  was  thought 
to  contain  a  malignant  growth.  Dr.  Cryer  rejected  this  interpretation, 
saying  that  the  antrum  must  have  been  of  the  size  shown  in  the  radio- 
graph before  the  formation  of  the  second  and  third  molars,  and  that  the 
large  antrum  was  responsible  for  the  pinched-together  condition  of  their 


238 


DENTAL   RADIOGRAPHY 


Fig.    374.     Lateral    view    of   the    same    case    illustrated    in    Fig.    273.      This    radiograph    shows   the 
impacted   tooth   clearly.      (Radiograph   by    Pfahler   of   Philadelphia.) 


roots.  He  theorized  further,  accounting  for  the  pain  the  patient  suffered 
by  surmising  that  the  pinched  condition  of  the  roots  of  the  third  molar 
was  causing  pressure  on  the  dental  pulp.  In  his  description  of  the  case 
Dr.  Cryer  does  not  mention  the  faulty  canal  filling  in  the  second  molar 
as  a  possible  cause  for  the  pain.  Both  molar  teeth  were  extracted  and 
the  patient  was  freed  from  neuralgia. 

49.  Co  Cocate  Torcign  Bodies,  Sucb  as  tooth  Roots  or  Broaches,  in  the  flntrum. 

Fig.  277  shows  a  piece  of  tooth  root  in  the  an- 

TiflS.  277  and  27$.       trum.     It  is  a  portion  of  the  second  bicuspid,  which 

had  been  extracted  (?)  about  a  week  previous  to  the 

time  when  the  patient  presented  to  Dr.  Virgil  Loeb  for  treatment.     The 


THE  USES  OE  THE  RADIOGRAPH  IN  DENTISTRY    239 


Fig.  275.     Antrum  filled  with  lead  shot.     The  same  as  Fig.  271. 


Fig.   276.      The  dots  outline   a  very  large  antrum.      (Radiograph   by  Pfahler,   of   Philadelphia.) 


240 


DENTAL  RADIOGRAPHY 


Fig.   277. 


The  arrows  point  to  a  piece  of  tooth  root  in  the  antrum, 
of   St.   Louis.) 


(Radiograph    by   Carman, 


first  molar  was  extracted,  an  opening  made  into  the  antrum  through  one 
of  its  alveoh,  and  the  piece  of  root  removed.  The  object  of  the  operation 
was  to  remove  the  piece  of  tooth  root  from  the  antrum.  This  was  accom- 
pHshed.  And  again  let  me  repeat  what  I  have  said  before :  An  operator 
may  make  a  greater  mistake  than  that  of  the  extraction  of  a  tooth — he 
may  conserve  the  tooth  at  the  expense  of  the  health  and  happiness  of  the 
patient.  Conservative  dentistry  often,  all  too  often,  means  conservation 
of  disease. 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY    241 


Fig.   278.     Same  case  as  Fig.   377   after   removal  of  the  piece  of  tooth  root. 

Carman,  of  St.  Louis.) 


(Radiograph   by 


Dr.    Cryer    says    of    Fig.    279:      "It    is    made 
?ig.  279.  from    a    patient    who    had    trouble    in    the    maxil- 

lary sinus  for  some  time.  The  picture  demon- 
strated that  a  piece  of  rubber  tubing,  which  had  been  used  for  drainage. 
had  slipped  into  the  antrum  and  become  lodged  in  the  region  of  the 
ostium  maxillare.  After  its  removal  and  a  brief  treatment,  the  part 
became  well." 


24^ 


DENTAL  RADIOGRAPHY 


Fig.    279.     The    arrows    point    to    a    piece    of    rubber    tubing    in    the    antrum.       (Radiograph    by 

Pancoast,    of   Philadelphia.) 


50.    to  Observe  Gases  of  Luxation  Before  and  After  Reduction. 

The  symptoms  of  dislocation  of  the  condyle 
Tigs.  2$0  and  2SI.  from  the  glenoid  fossa  are  so  characteristic  that,  it 
seems  to  me,  even  the  most  inexperienced  should 
recognize  them  with  ease.  It  is  a  fact,  however,  that  the  case  illustrated 
in  Figs.  280  and  281  was  diagnosed  dislocation,  because  I  presume  the 
patient  could  not  get  the  anterior  teeth  together.  The  radiographs  show 
two  fractures.  Fig.  280  near  the  angle,  and  Fig.  281,  of  the  other  side  of 
the  jaw,  in  the  second  bicuspid  region. 

This   radiograph  is  by  Tousey,  of  New  York 
Tig.  2$2.  City,  and  is  one  of  the  clearest  radiographs  of  the 

temporo-mandibular   articulation    T   have   ever    seen 
made  from  a  living  subject. 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY    243 


Fig.  280.     The  arrows  point  to  a  fracture  of  the  jaw  in  the  region  of  the  angle.      (Radiograph 

by    Cole    and    Raper,) 


Fig,  381.     The  arrows  point  to  a  fracture  of  the  lower  jaw  just  posterior  to  the  second  bicus- 
pid.     The    opposite    side    of    the    same   jaw    radiographed   in    Fig     280        (Radiograph    grossly    re- 
touched)    (Radiograph    by    Cole    and    Raper.) 


244 


DENTAL  RADIOGRAPHY 


Fig.    2S2. 


Excellent    radiograph    of    the    temijoro-mandibular    articulatioii.      Made    from    a    livii 
subject.      (Radiograph    by   Tousey,    of   New   York    City.) 


Case:      Dislocation    of    the    condyle    from    the 
Tid$.  2$3  and  2$4.       glenoid   fossa.     Fig.  283  shows  the   condyle   A  an- 
terior >to  the  eminentia  art.icularis  B,    Fig.  284  of  the 
same  case  after  reduction.    While  i^t  fails  to  show  the  condyle  itself  clearly, 
it  shows  the  neck  of  the  condyle  and  demonstrates  that,  in  this  picture,  the 
condyle  A  is  on  the  other  side  of  the  eminentia  articularis  B. 


51.  Tn  Cases  of  fracture  of  the  Saw- 
Fracture  of  the  jaw  is  almost  always  accompanied  by  such  a  great 
deal  of  swelling  and  induration  that  digital  and  ocular  examination 
are  highly  unsatisfactory.  The  operator  who  treats  a  fracture  should 
know  just  where  and  what  kind  of  a  fracture  he  is  dealing  with.  If  there 
be  displacement  of  the  fragments,  he  must  know  how  much,  and  in  what 
direction,  the  displacement  occurs,  in  order  that  he  may  properly  readjust 
the  parts.    This  knowledge  can  be  gained  only  by  the  use  of  radiographs — 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY     245 


Fig.    383.      Dislocation     of    the    condyle    from     the    glenoid    fossa.       A,    condyle.       B,     eminentia 
articularis.       (Radiograph    by    Cole    and    Raper.) 


stereoscopic  radiographs  preferably  in  cases  where  there  is  considerable 
displacement  of  the  fragments. 

Fracture  at  the  symphysis.     The   appliance  on 
»♦    **♦  the  teeth  is  being  used  as  a  splint. 

Case   in  the   practice   of   Dr.   Cryer.     Fig.   286 

Tigs,  2$6  and  2$7.       shows  a  fracture  of  the  mandible  at  the  angle.     The 

body  of  the  jaw  is  displaced  downward.     Fig.  287  is 

of  the  same  case  after  reduction  and  adjustment  of  an  interdental  splint. 

While  the  apposition  of  the  fractured  ends  is  not  perfect  yet,  there  is  a 


246 


DENTAL  RADIOGRAPHY 


A    a 

Wk 

J 

L 

f^^^^^^^^^^i 

^^^^^^^Hh^^^^^^^HH^^HHBh^^^.  ^ . : 

Fig. 


284.      Same    as    Fig.    283    after    reduction    of    the    dislocation.      A,    condyle, 
articularis.       (Radiograph    by    Cole    and    Raper.) 


B,    eminentia 


very  great  improvement  over  the  condition  showed  in  Fig.  386,  and  I  be- 
Heve  the  apposition  to  be  as  near  perfection  as  human  ingenuity  is  capable 
of  carrying  it. 

Just  when  to  remove  a  spHnt  and  bandage  from  a  fracture  case  is 
always  a  problem.  The  splint  shown  in  Fig.  287  was  removed  at  the  end 
of  the  eighth  week.  Dr.  Loeb,  of  St.  Louis,  Mo.,  states  that  radiographs 
are  a  great  aid  in  determining  just  when  to  remove  splints. 


fig.  2$8. 


A  double,  comminuted  fracture  of  the  mandible 
four  months  after  the  accident.  The  bone  in  the 
region  of  the  fracture  is  necrotic. 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY     247 

52.    Tn  Cases  of  Jlnkylosis  of  the  Cemporo-manaibular  Articulation  or  tbc 
Joint  formed  by  tbc  Cootb  in  tbc  law. 

The  radiograph  is  of  value  in  cases  of  ankylosis  to  observe  the  cause 
of  the  ankylosis. 

Case :    A  miner  who  had  sustained  a  traumatism 

fig.  2$9.  resulting  in  ankylosis.    The  ankylosis  had  existed  for 

several  months  at  the  time  Fig.  289  was  made.     The 

dots  outline  the  missing  parts,  i.e.,  the  anterior  border  of  the  ramus  and 


Fig.  385.     Fracture  of  the  mandible  at  the  symphysis.      (Radiograph  by   Blum,  of  New  York  City.) 

the  coronoid  process.  The  disease  of  the  bone  could  not  have  failed  to 
affect  the  temporal  and  masseter  muscles.  It  is  my  belief  that  in  this  case 
the  true  muscular  tissue  was  destroyed  and  replaced  with  cicatricial  tissite, 
which  condition  caused  a  false  ankylosis.  I  consulted  two  surgeons,  but 
neither  was  able  to  suggest  a  corrective  operation. 

An  orthodontist  was  unable  to  move  a  tooth  into  proper  occlusion. 
He  referred  the  case  to  me,  thinking  perhaps  the  presence  of  a  super- 
numerary tooth  body  was  responsible  for  the  immobility  of  the  tooth.  A 
radiograph  demonstrated  the  absence  of  any,  such  body,  and  showed  that 
the  tooth  had  practically  no  peridental  membrane  at  all.  There  was  a 
condition  of  partial  ankylosis,  to  overcome  which  it  was  necessary  for  the 
orthodontist  to  reinforce  his  anchorage  and  exert  more  force  on  the  re- 
fractory tooth.  I  do  not  print  a  radiograph  of  this  case  because  of  the 
great  difficulty  of  showing  the  peridental  membrane,  or  the  absence  of  it, 
in  a  half  tone. 

§?.   Co  Observe  tbe  field  of  Operation  before  and  after  Resection  of  tbc  mandible. 

Resection  of  the  mandible  is  a  difficult,  radical  operation,  and  one 
which  has  been  performed  comparatively  few  times.  With  the  excep- 
tion of  Dr.  Ballin  {Items  of  Interest,  June,  igo8),  operators  who  have 
done  this  operation  have  not,  so  far  as  I  am  able  to  karn,  availed  them- 


248 


DENTAL  RADIOGRAPHY 


Fig.    286.     Fracture   at   the   angle   of   the   mandible.      Displacement   of    fractured   ends.       (Radio- 
graph   by    Pancoast,    of    Philadelphia.) 


Fig.    887.     The    same    as    Fig.    286    after    reduction    and    adjustment    of    an    interdental    splint. 
(Radiograph    by    Pancoast,    of    Philadelphia.) 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY     249 


Fig.    288.     Double    comminuted    fracture    of    the    mandible.      That    the    reader    may    understand 
the    picture,    observe    the    following:      A.    zygomatic    arch;    B,    sigmoid    notch;    C,    upper    part    of 
ramus;   D,   one  fracture;   E,  the  other  fracture;   F,   fragment   of  bone  between  fractures.    (Radio- 
graph grossly  retouched.) 

selves  of  the  assistance  which  good  radiographs  of  the  case  would  have 
rendered.  Resection  of  the  mandible  might  become  necessary  as  a  re- 
sult of  an  existing  pathological  condition  of  the  bone,  or  it  might  be  done 
to  correct  a  bad  case  of  prognathism.  For  whatever  reason  the  operation 
may  be  done,  the  operation  itself  is  the  same,  in  that  a  piece  of  the  man- 
dible is  removed.  Consider  the  operation  for  prognathism,  for  example: 
A  piece  of  the  body  of  the  mandible  from  each  side  is  cut  out  and  re- 
moved. The  anterior  part  is  then  forced  back  and  the  cut  ends  of  the 
bone  (four  of  them)  wired  into  apposition.  That  anti-  and  post-operative 
radiographs  of  such  a  case  would  be  of  value  is  apparent. 

54.   Tn  Jill  0a$c$  of  facial  neuralgia  w\ib  an  Obscure  Biology. 

Cases  of  facial  neuralgia  with  an  obscure  etiology,  the  exciting  cause 
for  which  was  disclosed  by  the  radiograph,  have  already  been  described 
under  more  specific  headings — Figs.  159,  164,  176,  177,  179,  224,  250,  264, 
and  others.  Until  the  exciting  cause  is  found,  when  it  then  receives 
a  more  specific  name,  any  dental  pain  is  likely  to  be  referred  to  as 

npiiralcnn 


250  DENTAL  RADIOGRAPHY 

When  making  radiographs  to  learn  the  cause  of  trifacial  neuralgia, 
it  is  expedient  usually  to  make  a  large  plate  picture  of  the  affected  side. 
This  radiograph  can  then  be  studied  and,  if  some  lesion  is  discovered, 
another  radiograph  of  the  particular  region  of  the  lesion  made  on  a  small 
film.  The  second  radiograph,  on  the  film,  will  be  clearer  than  the  one  on 
the  plate,  and  will  verify  or  disprove  the  findings  in  the  larger  picture. 


Fig.    289.     The    dots   outline   the   missing   parts — i.e.,    the    anterior    border    of    the    ramus    and    the 
coronoid   process.      (Radiograph   by   Cole  and   Raper.) 

Case :  Married  woman,  middle  age,  suflfered 
Tigs.  2^0  and  2^1.  from  pains  in  the  region  of  the  upper  bicuspids.  The 
dentist  could  find  no  lesion  that  might  be  responsible 
for  the  trouble.  A  radiograph  (Fig.  290)  was  made,  but  does  not  show 
the  upper  teeth  clearly.  It  does,  however,  show  a  shadow  in  the  body  of 
the  mandible  in  the  region  of  the  lozver  first  molar,  which  tooth  is  missing 
from  the  jaw.  A  radiograph  (Fig.  291)  of  the  region  in  which  the 
shadow  appeared  was  made  on  a  small  film  held  in  the  mouth.  The  film 
was  not  placed  in  exactly  the  proper  position  and,  as  a  result  of  this  mis- 
take, pictures  only  a  part  of  the  lesion.  It  shows  the  crown  of  a  super- 
numerary lower  bicuspid  with  three  supernumerary  bodies  (denticles) 
above  it.  Though  the  lesion  in  the  lower  jaw  was  not  at  the  location  in 
which  pain  occurred,  it  was  very  likely  responsible  for  the  neuralgia. 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY     251 

The  patient  would  not  submit  to  an  operation.  The  case,  if  not 
operated  upon,  will  probably  progress  to  a  large  dentigerous  cystic  tumor. 
Evidence  of  this  can  already  be  noticed  in  Fig.  290  by  the  lack  of  normal 
density  of  the  surrounding  bone. 


Fig.   290.      The  arrow  points  to  a  shadow  in  the  body  of  the  mandible.      (Radiograph   by   A.    M. 

Cole,  of  Indianapolis.) 


Case :     Married  woman,  physician's  wife,  about 
Tig.  292.  forty-eight   years   old,   had  suffered   for  twenty-five 

or  thirty  years  with  attacks  of  neuralgia  occurring 
four  or  five  times  a  year,  each  attack  lasting  for  several  days.  None  save 
dental  operations  were  performed,  though  she  received  palliative  treat- 
ment for  ear,  mastoid  cells  and  antrum  trouble.  No  treatment  gave  relief. 
She  left  her  home  in  Indiana  and  spent  one  winter  in  South  Carolina, 
hoping  the  rnilder  climate  would  ward  off  the  attacks  of  pain,  but  this 
proved  futile.     At  no  time  did  her  temperature  rise  above  normal,  prov- 


252  DENTAL  RADIOGRAPHY 

ing,  or  seeming  to  prove,  that  whatever  the  irritation,  there  was  little  or 
no  suppuration  attending  it.  A  radiograph  (Fig.  292)  was  finally  made, 
and  showed  an  impacted  upper  third  molar.  This  tooth  was  removed, 
and  since  then,  now  over  four  years  ago,  she  has  not  had  a  single  attack 
of  neuralgia. 

Attention  is  called  to  the  fact  that  up  to  the  time  of  making  the  radio- 
graph this  was  a  typical  case  of  idiopathic  facial  neuralgia. 


Fig.  291.  The  same  case  as  Fig.  290.  A  radiograph  of  the  upper  part  of  "the  shadow."  It 
shows  the  crown  of  a  supernumerary  bicuspid  with  three  denticles  above  it.  The  white  spot 
at  the  apex  of  the  second  bicuspid  is  caused  by  an  air  "bell"  attaching  itself  to  the  film  in  that 
region  at  the  time  it  was  in  the  developing  solution.     (Radiograph  by  A.  M.  Cole,  of  Indianapolis.") 


55.   to  Observe  tbe  Tnferior  Dental  GanaK 

Often,  but  not  always,  we  are  able  to  radiograph  the  inferior  dental 
canal.  (See  Fig.  190.)  To  the  man  contemplating  resection  of  the  in- 
ferior dental  nerve  anywhere  throughout  its  course  in  this  canal  a  radio- 
graph showing  the  location  of  the  canal  would  be  of  value. 

Dr.  Virgil  Loeb,  of  St.  Louis,  reports  a  case  of  anesthesia  of  the 
lower  lip,  and  that  part  of  the  face  on  one  side  which  receives  its  nerve 
supply  from  the  nerves  passing  through  the  mental  foramen.  The  anes- 
thesia followed  the  extraction  of  a  lower  third  molar.  A  radiograph  of 
the  case  showed  that  the  roots  of  the  third  molar  had  penetrated  the  in- 
ferior dental  canal.  Knowing  this,  it  was  deduced  that,  at  the  time  of 
extraction,  the  inferior  dental  nerve  had  been  stretched,  and  a  few  fibers 
torn  at  the  mental  foramen.  Lately  I  have  personally  observed  such  a 
case.  I  do  not  print  radiographs  of  either  Dr.  Loeb's  or  my  own  case, 
because  they  are  not  clear  enough  to  permit  of  good  half-tone  reproduc- 
tion. Such  cases  as  the  ones  now  under  consideration  recover  slowly,  the 
time  required  varying  from  one  to  several  months.  Treatment  with  the 
high-frequency  current  may,  or  mav  not.  hasten  recovery  slightly.  Though 
slow,  complete  recovery  may  be  expected. 


THE  USES  OE  THE  RADIOGRAPH  IN  DENTISTRY     253 

Immediately  after  the  filling  of  the  canals  of  a  lower  second  molar  a 
patient  suffered  most  severe  pain  in  the  region  of  the  filled  tooth.  A 
radiograph  was  made  and  showed  the  canal  filling  penetrating  the  apical 
foramen  of  the  distal  root,  projecting  into  the  inferior  dental  canal,  and 


Fig.    292.     The  arrow   points   to   an   impacted   upper,    tliird  molar,   tlie   cause    of    "idioparliic"    neu- 
ralgia,  from   which   the    patient    had    suffered   recurrently    for   from   between    twenty-five   to   thirty 
years.      (Radiograph   by  A.   M.    Cole,  of  Indianapolis.) 

doubtless  pressing  the  inferior  dental  nerve.  An  effort  to  remove  the 
canal  filling  met  with  failure,  and  the  tooth  was  extracted  to  relieve  the 
patient  of  the  intense  pain.  Again  I  do  not  print  radiographs  of  the  case 
because  the  prints  are  not  sufficiently  clear  to  permit  of  good  half-tone 
reproductions. 

»  56.  Tn  Cases  of  Eudwig's  Angina. 
Angina  is  defined  in  Borland's  Medical  Dictionary  as  "any  disease  or 
symptom  characterized  by  spasmodic  suffocative  attacks" ;  Ludwig's 
angina  as  "purulent  inflammation  seated  around  the  submaxillary  gland." 
Whenever  there  is  a  pus  sinus  opening  on  the  neck  in  the  region  of  the 
submaxillary  gland,  the  patient  is  said  to  have  Ludwig's  angina.  This  is 
the  popular  application  of  the  term,  and  it  seems  to  the  writer  unfor- 


254 


DENTAL  RADIOGRAPHY 


Fig.   293.      Photograph   of  a  case   of  so-called   Ludwig's  angina.      Also   a   radiograph   of   the  case 
showing   an    abscess    of   the   first   permanent    molar.      The   fistulous  tract   cannot    be    seen. 


tunate,  for  there  is  seldom  angina — i.e.,  suffocative  attacks — in  these  cases 
of  suppuration  of  the  neck. 

Fig.  293  is  a  photograph  of  a  case  of  so-called 
Tig.  293.  Ludwig's  angina  occurring  in  a  child  ten  years  of 

age.  The  accompanying  radiograph  of  this  case 
shows  an  abscessed  lower  first  molar,  which  was  responsible  for  the  sinus 
on  the  neck.  The  arrow  points  to  a  notch  in  the  lower  border  of  the  body 
of  the  mandible.  Extraction  of  the  lower  first  molar  and  curettement 
of  the  alveoli  was  all  that  was  necessary  to  effect  a  cure  in  this  case.  Had 
the  patient  been  older,  or  not  so  vigorously  healthful,  the  slightly  necrotic 
area  pointed  to  by  the  arrow  would  have  required  curettement  through  a 
facial  opening.  The  radiograph  happens  to  demonstrate  the  congenital 
absence  of  a  lower  second  bicuspid. 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY     255 

Dr.  H.  R.  Sparrevohn,  of  Los  Angeles,  reported  a  case  of  "Ludwig's 
Angina"  in  the  June  number  of  the  Dental  Cosmos,  1910.  The  patient 
was  receiving  hospital  treatment  for  suppuration  of  the  glands  of  the 
neck,  when  Dr.  Sparrevohn  examined  the  case,  had  radiographs  made, 
and  pronounced  the  trouble  due  to  an  impacted  lower  third  molar,  which 
could  be  seen  clearly  in  the  radiograph,  and  in  appearance  was  similar  to 
Fig.  159,  Neither  the  patient  nor  the  attending  physicians  could  be  con- 
vinced that  his  diagnosis  was  correct.  (Had  the  fistula  been  injected 
with  bismuth  paste  and  a  radiograph  made  there  would  have  been  no 
chance  for  disoute.)  Dr.  Sparrevohn  closed  his  report  of  the  case  as  fol- 
lows :  'T  should  be  thankful  to  readers  of  the  Dental  Cosmos  if  they 
would  express  themselves  as  to  the  correctness  of  my  diagnosis.  At  pres- 
ent I  am  much  discredited,  especially  by  the  medical  men  connected  with 
the  case." 

Dr.  Herbert  Mcintosh,  a  physician,  answered  Dr.  Sparrevohn  in 
Dental  Cosmos,  October,  1910.  He  said  in  part :  "I  think  there  can  be 
scarcely  any  doubt  that  the  malposed  molar,  of  which  very  good  radio- 
grams were  presented,  was  the  cause  of  the  serious  symptoms  reported. 
Anyone  who  has  had  experience  in  the  skiagraphing  and  observing  of 
such  cases  would  have  no  hesitation  in  suspecting  dental  irritation  as  the 
origin  of  the  symptoms  reported  in  the  case.  In  general,  the  medical  man 
is  too  apt  to  overlook  the  reflex  irritation  produced  by  the  teeth.  There 
is  evident  need  of  skiagraphy  to  clear  up  these  obscurities  of  diagnosis  in 
conditions  of  the  face  and  cranium.  There  should  likewise  be  a  greater 
readiness  to  admit  the  importance  which  teeth  have  in  producing  patho- 
logical conditions  of  the  tissues." 

I  believe  I  am  safe  in  saying  that  about  all  of  the  cases  of  so-called 
Ludwig's  angina  are  due  to  dental  lesions.  Yet,  referring  to  no  less  than 
a  dozen  medical  dictionaries  and  works  on  the  practice  of  medicine,  I 
find  that  none  of  them  even  mention  the  teeth  as  an  etiological  factor  to 
be  considered.  These  books  state  that  the  disease  is  caused  by  diphtheria, 
erysipelas,  syphilis,  tuberculosis,  and  that  it  occurs  epidermically  and  idio- 
pathically.  It  is  therefore  not  surprising  that  Dr.  Sparrevohn's  diagnosis 
was  discredited. 

As  is  indicated  by  the  remarks  of  Dr.  Mcintosh,  many  medical  men 
are  more  enlightened  than  the  authors  of  the  books  to  which  I  have  re- 
ferred. But,  on  the  other  hand,  many  of  our  brothers  in  the  practice  of 
general  medicine  need  education  along  this  line.  For  example,  a  physi- 
cian of  my  acquaintance,  a  specialist  on  the  treatment  of  tuberculosis, 
treated,  and  treated  without  benefiting,  a  case  quite  similar  in  appearance 
to  Fig.  293,  giving  the  usual  anti-tubercular  treatment,  including  the  ad- 
ministration of  bacterine.     The  patient's  mouth  had  never  been  examined 


256  DENTAL  RADIOGRAPHY 

by  a  dentist,  and  radiographs  of  the  case  were  not  made,  nor  were  either 
of  these  things  done  after  I  suggested  them,  because  the  physician  thought 
it  so  highly  improbable  that  the  teeth  could  cause  such  a  condition. 

To  illustrate  the  grave  nature  of  the  symptoms  in  some  of  these  cases 
permit  me  to  report  the  following  case : 

Young  man,  age  twenty-three,  suffered  from  what  was  diagnosed 
pharyngeal  abscess.  Confined  to  the  house  for  a  month,  and  lost  thirty 
pounds.  A  change  of  physicians  brought  in  a  man  on  the  faculty  of  the 
Indiana  Dental  College.  It  became  necessary  to  make  an  external  in- 
cision to  permit  the  escape  of  a  great  quantity  of  pus.  And  let  me  say 
that  because  the  incision  was  made  on  a  line  with,  instead  of  at  right 
angles  to,  the  fibers  of  the  muscle,  the  resultant  scar  is  hardly  noticeable. 
The  writer  was  called  in  consultation.  I  did  not  do  radiographic  work, 
nor  appreciate  its  importance  at  this  time,  or  the  doubt  in  my  mind  as  to 
the  correctness  of  my  diagnosis  might  have  been  eliminated.  The  patient 
could  not  open  the  mouth,  but  instruments  passed  along  the  vestibule  of 
the  mouth  came  in  contact  with  the  corner  of  what  I  suspected  to  be  an 
impacted  lower  third  molar.  The  mouth  was  opened,  the  tooth  found 
and  removed,  and  the  patient  recovered  immediately.  The  impacted  tooth 
was  not  decayed. 

The  radiograph  should  be  used  in  all  such  cases  of  suppuration  about 
the  face  and  neck. 

A  very  large  abscess  about  the  apices  of  the  roots 
«j  of  the  lower  first  molar.     In  facial  fistula  cases  it  is 

best  to  make  a  radiograph  which  will  include  the  en- 
tire side  of  the  jaw.  I  have  seen  a  case  recently  where  both  a  lower  sec- 
ond molar  and  a  first  bicuspid  were  involved  in  the  production  of  a  facial 
fistula. 

57.    Tn  €a$e$  of  Tnsomnia.  neurasthenia,  Tnsanity  and  Kindred  nervous  Disorders. 

If  Dr.  Henry  S.  Upson,  of  Cleveland,  were  a  dentist,  his  assertion 
that  dental  lesions  may,  and  do,  cause  insanity,  would  be  met,  not  alto- 
gether unfairly,  with  the  argument  that,  in  the  practice  of  his  specialty, 
Dr.  Upson  had  developed  a  rare  case  of  myopia,  and  could  no  longer  see 
past  his  especial  field  and  consider  other  etiological  factors.  But  Henry 
S.  Upson  is  not  Henry  S.  Upson,  dentist;  he  is  Henry  S.  Upson,  M.D., 
Professor  of  Diseases  of  the  Nervous  System  at  the  Western  Reserve 
University,  and  Attendant  Neurologist  to  the  Lakeside  Hospital,  Cleve- 
land, Ohio. 

The  situation  as  it  stands  to-day  is  this :  Dr.  Upson  claims  that  im- 
pacted teeth  and  chronic  alveolar  abscesses  cause  insomnia,  neurasthenia 
and  insanity.  He  gives  histories  of  radiographically  illustrated  cases, 
which  have  been  cured  by  extraction  of  the  impacted  or  abscessed  teeth, 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY     257 


p"ig.  294.     Dento-alveolar  abscess  of  the  lower  first  molar  discharging  on  the  face. 


and  he  asks  a  question:  "//  a  diseased  uterus  can  cause  insanity  (and  it 
is  believed  that  it  can),  then  why  not  dental  disease?"  The  nervous  con- 
nection between  the  teeth  and  brain  is  much  more  intimate  than  that  be- 
tween the  uterus  and  the  brain.  No  one  answers  Dr.  Upson's  question, 
and  so  far,  no  one  has  in  any  way  tried  to  prove  Dr.  Upson  wrong  in  his 
belief  that  the  teeth  are  responsible  for  grave  nervous  disorders.  We 
must  then,  in  fairness,  accept  what  he  says  as  the  truth,  until  we  are  able 
to  show  wherein  he  is  mistaken. 

To  give  you  an  idea  of  the  importance  of  dental  lesions  as  a  causa- 


258  DENTAL  RADIOGRAPHY 

tive  factor  in  the  neurosis,  as  promulgated  by  Dr.  Upson,  I  quote  from 
the  doctor's  book,  ''Insomnia  and  Nerve  Strain" : 

"Of  the  viscera  responsible  for  the  more  obscure  cases  of  ne^-vous 
and  mental  derangement,  1  have  no  hesitation  in  designating  the  teeth  as 
the  most  important.  This  is  not  only  on  account  of  the  common,  almost 
universal  occurrence  of  dental  diseases,  but  because  these  organs  move, 
during  the  period  of  their  development,  through  the  solid  framework  of 
the  jaw,  highly  innervated  and  clothed  by  a  membrane  sensitive  to  im- 
pact and  to  corrosive  toxins." 

That  Dr.  Upson  has  met  with  skepticism  on  the  part  of  his  brother 
practitioners  is  suggested  I  believe  by  the  following,  quoted  again  from 
the  book,  "Insomnia  and  Nerve  Strain" : 

"There  seems  to  exist  among  physicians  not  only  a  disregard  but  a 
distinct,  though  mild  dislike  of  the  teeth  as  organs  to  be  reckoned  with 
medically,  they  being,  as  it  were,  an  Ishmael,  not  to  be  admitted  to  their 
pathologic  birthright.  Lauder  Brunton's  essay  on  the  subject  is  too  little 
known  and  heeded,  and  few  such  systematic  attempts  have  been  made  to 
correlate  their  disorders  with  the  suffering  of  the  human  race,  except  for 
the  obvious  phenomena  of  pain.  Ordinary  pain  at  a  distance,  as  head- 
ache or  neuralgia,  due  to  the  teeth,  though  well  known,  is  commonly  dis- 
regarded. Even  the  various  reflex  nervous  phenomena  in  children,  con- 
vulsions, fretfulness,  and  fever,  are  not  now  ascribed  to  the  irritation 
either  of  teething  or  of  dental  caries,  but  to  digestive  disorders.  The 
state  of  recent  opinion,  as  enshrined  in  epigram,  is  that  'The  result  of 
teething  is  nothing  but  teeth.'  " 

My  readers  may  ask  what  has  all  this  to  do  with  dental  radiography? 
Just  this :  the  radiograph  should  be  used  more  extensively,  as  Dr.  Upson 
has  used  it,  in  a  search  for  dental  lesions  in  cases  of  the  various  nerve 
disorders,  for  Dr.  Upson  states  "The  lesions  can  seldom  be  observed  by 
any  means  save  the  use  of  the  X-rays." 

Though  I  would  like  to  print  a  radiograph  and  history  of  all  of  the 
different  neuroses  including  insomnia,  neurasthenia,  mania,  hysteria,  mel- 
ancholia and  dementia,  it  would  hardly  be  in  keeping  with  a  work  of  this 
kind,  and  I  shall  therefore  give  but  one  case,  which  is  more  or  less  typical. 

Case :    Melancholia  and  insomnia.    "An  unmar- 
f Ig,  295.  ried  woman,  twenty-seven  years  old,  a  teacher,  for 

a  year  had  been  profoundly  melancholy  with  intract- 
able insomnia,  delusions  of  various  deadly  sins,  and  entire  hopelessness 
of  recovery.  Restlessness  was  extreme,  tonic  and  local  uterine  treatment 
were  of  no  avail.  As  a  last  resort  the  teeth  were  examined.  They  were 
apparently  in  perfect  condition.  A  skiagraph  (Fig.  295)  showed  an  im- 
pacted upper  third  molar  tooth  pressing  against  the  second  molar,  a  con- 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY    259 

dition  obviously  capable  of  causing  irritation.  The  symptoms,  in  about 
a  week  after  the  removal  of  the  tooth,  began  to  improve.  Recovery  was 
complete  in  six  or  eight  weeks,  and  has  persisted.  There  had  been  at  no 
time  pain  or  other  localizing  symptoms." 


Fig.    295.      Impacted    upper    third    molar,    causing    melancholia    and    insomnia.       (Radiograph    by 

Lodge,     of    Cleveland.) 

In  concluding  our  consideration  of  this  subject,  I  quote  from  a  recent 
paper  by  Dr.  Upson  : 

"The  following  is  a  tabulated  statement  of  cases  of  neurasthenia  and 
the  psychoses  seen  in  private  practice  during  about  two  and  a  half  years, 
in  which  skiagraphic  examinations  of  the  teeth  and  jaws  were  made. 
These  results  represent  the  first  stumbling  efforts  in  a  new  and  unknown 
field,  and  so  do  not  adequately  show  what  may  be  accomplished  by  skill 
and  careful  endeavor  along  the  same  line : 

Num-        Opera-        Recov-     Conval-  Im-       Unim-       No 

lier  tion  ery  escent      proved     proved     Data 

Manic  depressive  type 11  9  5  ..  2  ..  2 

Dementia  precox 10  8  5  i  ..  2  .. 

Psychosis 4  4  i  2  ..  ..  i 

Insomnia 7  6  2  ..  4 

Neurasthenia   26  15  i  4  6  i  3 


58  42  T4           7  12  3           6 
The  following  is  a  separate  statement  of  the  cases  of  impaction  in- 
cluded above  :                                         -^^^,  Opera-  Recov-  Conval-  Tm-       Unim-       No 

ber             tion             ery  escent  proved     proved     Data 

Manic  depressive  type 5           3           2  ..  i 

Dementia  precox 7  5  4  i 

Psychosis 2  2  i  i 

Insomnia 3           2  ..  ..  2 

Neurasthenia  13           9  ..           4  2  i  2 


30 


21 


26o  . 


DENTAL  RADIOGRAPHY 


5$.   Tn  0a$e$  of  Perioaic  l)e(idacbe$. 

Irritation  of  the  trifacial  nerve  may  cause  headache.  The  irritation 
may  be  due  to  such  lesions  as  an  impacted  tooth,  a  chronic  abscess,  or  a 
cementoma,  for  examples. 

"After  the  removal  of  the  malposed  impacted 
Tig.  296.  cuspid  seen  in  Fig.  296,  severe  headaches  which  she 

(the  patient)  had  had  once  or  twice  a  week  for  man}' 
years  ceased  immediately."* 

Several  cases  similar  to  the  one  cited  above  have  been  reported  in 
recent  dental  literature. 


Fig.  296 


Fig.  297 


Fig.    296.      Malposed    impacted    lower    cuspid,    responsible    for    periodic    headaches.       (Radiograpli 

by    Thomas,    of    Cleveland.) 

Fig.   297.      An  impacted   upper   cuspid,   which  caused  blinking  of  the  eyes.      (.\fter 
Dr.    Varney    Barnes.) 


TIfl.  297. 


59.    Tn  €a$e$  of  Tacml  6e$ticulatory  tic.  (Spasmodic  twitcMng  of  a  Set 
of  facial  muscles.) 

"An  impacted  upper  cuspid  which  caused  blink- 
ing of  the  eyes."** 
Dr.  Barnes  also  reported  a  case  of  twitching  of  the  facial  muscles  on 
one  side.  On  the  corresponding  side  two  supernumerary  teeth  were 
found.  I  have  been  unable  to  learn  from  Dr.  Barnes  whether  removal  of 
the  supernumerary  teeth  effected  a  cure.  Dr.  Barnes  agrees  with  Dr. 
Upson  thus  far  at  least :  both  men  are  of  the  opinion  that  impacted 
teeth  may  be  responsible  for  varied  and  grave  nerve  disorders.     Dr.  Up- 


*Dr.  Henry  S.  Upson,  Cleveland,  Ohio. 
**Dr.  Varney  E.  Barnes,  Cleveland,  Ohio. 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY     261 

son's  treatment  has  always  been  extraction,  while  Dr.  Barnes  advocates 
orthodontic  procedures,  such  as  enlarging  the  dental  arches  and  elevation 
of  the  impacted  tooth. 

60,    to  Jlllay  the  Tears  of  a  1>ypochondriac. 

Every  practitioner  of  dentistry  and  medicine  has  trouble  with  hypo- 
chondriacal patients,  patients  suffering— and  actually  suffering— from 
some  imaginary  ailment.     What  these  patients  need  is  psychic  treatment. 


Fig.    298.      The    radiograph    demonstrates    the    absence    of   a    piece    of    the    lateral    root   above    the 

lateral    dummy   and    shows    the    canals    of    the    central    and    cuspid    well   filled    and    the    tissues    at 

their  apices  healthy.      (Radiograph  grossly   retouched.) 


To  be  sympathized  with — or  a  better  way  to  state  it  would  be  to  say  "un- 
derstood"— and  at  the  same  time  shown  that  their  trouble  lies,  not  in  any 
pathologic  lesion,  but  in  faulty  habits  of  thought. 

Case :    Young  lady,  age  about  twenty-three,  com- 
Tifl.  2$S.  plained  of  obscure  indefinite  pains  in  the  region  of  a 

bridge  extending  from  central  to  cuspid,  which  pains 
she  declared  were  due  to  an  unremoved  portion  of  the  lateral  incisor  root. 
Having  seen  the  lateral  root  when  it  was  extracted,  and  superintended  the 
treatment  of  the  central  and  cuspid,  and  the  making  of  the  bridge,  and 
knowing  the  patient — in  short,  knowing  the  complete  history  of  the  case — 
I  was  inclined  to  believe  that  the  trouble  with  the  bridge  lay  in  the  diseased 
imagination  of  the  patient.  After  treating  the  case  with  counter-irritants 
once  or  twice,  each  time  conversing  freely  with  the  patient  concerning  her 
symptoms,  and  failing  to  observe  any  clinical  signs  of  a  pathologic  lesion, 
I  became  convinced  that  my  original  surmise  was  correct,  and  that  the 


262  DENTAL  RADIOGRAPHY 

teeth  involved  in  the  bridge  were  causing  no  pain.  I  positively  knew 
there  was  not  a  piece  of  the  lateral  root  above  the  artificial  dummy,  as  the 
patient  insisted.  Having  arrived  at  this  conclusion,  1  proceeded  as  tact- 
fully and  kindly  as  I  could  to  explain  my  belief  to  the  patient.  Where- 
upon she  broke  down  and  cried,  displaying  definite  symptoms  of  hysteria. 
I  want  it  distinctly  understood  that  I  did  not  blame  the  patient  for 
her  condition ;  that  I  was  not  out  of  patience  with  her ;  that  I  did  not 
tell  her  there  was  nothing  the  matter  with  her — for  there  was,  though  the 
seat  of  the  trouble  was  not  the  bridge.  And  this  I  tried  to  make  her  un- 
derstand. After  she  had  recovered  somewhat  from  her  crying,  I  said : 
"Now  I  do  not  want  to  take  that  bridge  off,  for  I  know  there  is  no  root 
beneath  it.  I  do  not  need  to  look  and  see,  as  you  ask  me  to.  But  I  know 
a  way  of  looking  at  the  bridge  so  we  can  botli  see  it  if  there  is  any  root 
there,  or  if  either  of  the  crowned  teeth  are  at  all  diseased.  If  I  can  show 
you  beyond  the  shadow  of  all  doubt  that  there  is  no  root  there,  will  you 
believe  that  what  I  have  been  telling  you  is  perhaps  true,  that  the  bridge 
is  all  right,  and  that  you  are  falling  into  faulty  habits  of  thought?"  She 
said  she  would. 

The  radiograph  (Fig.  298)  shows  there  is  no  root  above  the  lateral 
dummy,  that  the  canals  of  the  central  and  cuspid  are  properly  filled,  and 
that  the  tissues  at  their  apices  are  not  diseased.  The  radiograph  of  her 
own  case,  together  with  several  others  showing  roots  above  bridges,  ab- 
scesses and  perforations,  were  shown  and  explained  to  the  patient.  I  did 
not  attempt  to  force  her  to  admit  that  I  had  been  right  in  my  diagnosis  of 
her  case,  nor  did  she  do  so  verbally ;  but  she  has  not  returned  for  further 
treatment,  and  she  still  wears  the  bridge. 

61.   Tn  €asc$  Ulbcrc  the  Patient  Cannot  Open  tbe  moutb  lUlde  enougb 
for  an  Ocular  examination. 

An  impacted  lower  third  molar  sometimes  causes  a  false  ankylosis. 
We  suspect  the  presence  of  the  impacted  tooth,  but  are  unable  to  demon- 
strate it  except  by  the  use  of  the  radiograph  made  extra-orally  (Fig. 
108).  With  the  radiograph  to  confirm  suspicions  and  show  the  exact 
location  of  the  offending  tooth,  the  operator  may  proceed  to  anesthetize 
the  patient,  force  the  mouth  open  with  a  mouth  prop  and  extract  the 
tooth. 

Fig.  299  is  a  case  in  which  the  mouth  could 
fifl.  299*  not  be  opened  because  of  the  inflammation  caused  by 

the  impacted  lower  third  molar  seen  in  the  radio- 
graph, 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY     263 

62.  Tn  Research  Ulork  to  Study  Osteology,  the  Development  of  the  teetb,  Hction  of 
Bismuth  Paste,  Bone  Production  and  Destruction,  Changes  Occurring  in  the  tem- 
poro-mandibular  Jfrticulation  Ulhen  lumping  the  Bite,  Blood  Supply  to  Parts,  Re- 
sorption of  Ceeth  and  the  Causes  for  Tt,  etc. 

The  value  of  the  radiograph  to  the  man  who  is  looking  for  the  just- 
how  and  why  of  things  is  clearly  apparent.  It  obviates  the  necessity  of 
conjecture,  and  gives  us  simple,  indisputable  facts.     Many  problems  now 


Fig.    299.      Impacted    lower    third    molar,    causing    a    false    ankylosis.       (Radiograph    by    Graham. 

of  Detroit.) 


confronting  the  dental  scientist  can  be  solved  only  by  the  intelligent  and 
persistent  use  of  the  X-rays. 

It  is  not  my  intention  now  to  tell  of  all  the  different  uses  to  which 
the  radiograph  has  been  and  may  be  put  in  the  broad  field  of  dental 
scientific  research.     I  could  not  if  I  tried.     I  shall  mention  but  a  few. 

Dr.  Joseph  Beck,  by  the  use  of  the  stereoscopic  radiographs,  is  mak- 
ing a  comparative  study  of  the  pneumatic  sinuses  of  man  and  the  lower 
animals. 


264 


DENTAL   RADIOGRAPHY 


Dr.  Johnson  Symington  and  Dr.  J.  C.  Rankin  have  recently  pubHshed 
a  book,  "An  Atlas  of  Skiagrams,"  illustrating,  in  twenty  radiographs,  the 
development  of  the  teeth"  and  jaws  from  birth  to  the  age  of  sixteen  years. 

I  have  demonstrated  the  action  of  bismuth  paste  in  one  case.  (Fig. 
223.)  No  definite  conclusions  should  be  drawn  from  this  single  case.  The 
field  of  research  work  along  this  line  is  still  wide  open  and  inviting  in- 
vestigation. 


Fig.  300.  Fig.  ;iU1. 

Fig.    300.      Abscessed    upper    lateral    incisor,    causing    disintegration    of    the    built-in    bone    at    the 
ape.x  of  the  central  incisor.      (Radiographed  by   Schamberg,   of  New   York  City.) 

Fig.  oOl.  The  same  as  Fig.  .300  after  treatment  and  filling  of  the  canal  of  the  lateral.  Bone  is 
being  rebuilt  into  the  abscess  cavity  at  the  apex  of  the  central.  (Radiographed  by 
Schamberg,   of  New   York   City. ) 


Bone  production  and  destruction  in  alveolar  abscesses  is  a  matter  of 
which  we  know  entirely  too  little.  A  systematic  radiographic  study  of 
the  subject  is  bound  to  result  in  the  disclosure  of  interesting  and  im- 
portant facts. 

A  question,  the  answer  to  which  is  of  extreme 
TiflS.  300  and  301.       importance  is,  "Do  alveolar  abscess  cavities  become 
filled  with  bone  after  the  abscess  is  cured  ?"*    My  ex- 
perience leads  me  to  believe  they  do ;  but  the  new  bone  may  not  be  quite  as 
dense,  and  it  is  susceptible  to  ready  disintegration  as  a  result  of  contiguous 
inflammation. 

Observe  Fig.  300,  a  case  from  the  practice  of  Dr.  R,  Otto- 
lengui.  Note  the  light  areas  at  the  apices  of  both  the  central 
and  lateral.  A  cursory  observation  of  the  radiograph,  and  a  failure 
to  consider  clinical  history,  would  result  in  the  diagnosis  of  abscess  of 
both  the  central  and  lateral.  Observe,  please,  however,  that  the  canal  of 
the  central  is  well  filled,  while  the  canal  of  the  lateral  is  not  filled  at  all. 

*  For  a   further  consideration  of  this   subject  see  Appendix  Chap.  XI. 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY     265 


5)  ^ 


o  i; 


g  Q 


S  o 


266  DENTAL  RADIOGRAPHY 

The  central  had  been  filled  three  years  previously  to  the  making  of  the 
radiograph,  and  there  had  been  no  recurrence  of  the  abscess  during  that 
time.  The  lateral  was  treated  and  its  canal  filled,  when  all  symptoms  of 
abscess  disappeared.  Fig.  301  was  made  after  the  canal  of  the  lateral  was 
filled.  What  I  shall  speak  of  now  I  fear  cannot  be  seen  in  the  accompany- 
ing  half-tone ;  but  it  can  be  observed  easily  in  the  negatives.  At  the  apex 
of  the  central  there  is  a  deposition  of  bone  in  the  old  abscess  cavity. 
The  bone  is  not  as  dense  as  the  surrounding  structure,  and  hence  the  out- 
line of  the  old  cavity  can  still  be  seen ;  but  it  is  sufficiently  dense,  so  that 
it  can  be  observed  distinctly,  and  especially  well  when  compared  with 
the  cavity  at  the  apex  of  the  lateral,  which  has  not  been  freed  from  in- 
fection long  enough  to  permit  of  an  osseous  formation  within  it. 

Just  what  changes  occur  in  the  temporo-mandibular  articulation  when 
"jumping  the  bite"  is  still  an  unsettled  question.  It  is  extremely  difficult 
to  radiograph  this  articulation,  but  it  can  be  done,  and  it  is  not  unreason- 
able to  expect  that  some  day  the  radiograph  will  show  us  just  what  occurs. 
Dr.  H.  A.  Ketcham,  of  Denver,  is,  and  has  been  for  some  time,  working 
in  this  field  of  research. 

Dr.  Cryer,  in  a  recent  article  on  the  study  of  blood  supply  to  the  jaws 
and  teeth,  printed  a  radiograph  of  a  disassociated  mandible  injected  with 
mercury.  How  well  blood  supply  may  be  studied  by  injecting  the  vessels 
with  bismuth  paste,  or  some  other  substance  opaque  to  the  rays,  then 
making  a  radiograph  is  obvious  and  most  encouraging  to  the  student. 

The  radiographs  are  of  a  little  girl  eleven  years 
Tifl.  302.  of  age.     They  demonstrate  the  congenital  absence  oi 

the  following  teeth:  In  the  upper  jaw  both  lateral 
incisors,  one  cuspid  and  one  bicuspid;  in  the  lower  jaw  three  bicuspids, 
making  in  all  seven  permanent  teeth  congenitally  absent  from  the  jaws. 
Despite  the  absence  of  the  permanent  teeth  resorption  of  the  roots  of  the 
temporary'  teeth  occurs,  showing  that  the  resorption  is  not  dependent  on 
the  eruption  of  the  permanent  teeth.  I  do  not  make  the  statement  that 
the  temporary  tooth  roots  resorb  independently  of  the  succedaneous  teeth 
because  of  what  1  see  in  the  radiograph  in  Fig.  302.  Fig.  302  but 
illustrates  what  has  been  observed  in  many  other  radiographs. 

Dr.  H.  A.  Ketcham,  with  the  aid  of  radiographs,  has  endeavored  to 
disprove  that  certain  orthodontic  procedures  caused  impaction  of  the 
third  molars. 

The  discussion  of  the  orthodontic  procedure  of 

Tigs.  303  and  304.       "opening  the  maxillary  suture"  is  one  in  which  the 

radiograph  is  yet  playing  an  important  role.     That 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY     267 

this  suture  can  be  opened  is  claimed  by  Dr.  Varney  C.  Barnes.  Figs.  303 
and  304  are  from  the  practice  of  Dr.  Barnes.  How  wide  it  may  be  opened, 
the  permanency  of  the  separation  of  the  bones,  and  the  benefits  to  be 
derived  from  the  operation  I  shall  not  discuss,  but  radiography  will  al- 
ways be  a  valuable  aid  in  determining  the  condition,  both  before  and  after 
treatment. 

In  the  discussion  of  a  paper,  read  at  a  dental  society  meeting.  Dr. 


Fig.  303.  Fig.  304. 

Fig.    303.      Before  attempting   to  open   the  maxillary   suture.      (Radiographed   by    Lodge,   of 

Cleveland.) 

Fig.    304.      Same    case    as    Fig.    303    fourteen    days    later,    after    attempt    to    open    the    maxillary 

suture.      (Radiographed   by    Lodge,    of    Cleveland.") 


Don  Graham  recently  said:  "If  the  radiograph  has  done  nothing  else  it 
has  proven  beyond  all  doubt  that  the  best  canal  filling  in  use  to-day  is 
gutta-percha." 

Also  radiographs  have  shown  us  that,  when  filling  canals  with  large 
apical  foramina,  we  would  better  force  a  little  gutta-percha  through  the 
apex  rather  than  to  fall  short  of  reaching  the  end  of  the  root.  Of  the 
two  mistakes,  the  former  is  less  likely  to  be  followed  by  abscess  formation. 

The  radiograph  shows  an  upper  cuspid  with  a 

Tig.  SOS.  perforation  to  the  mesial  through  the  side  of  the  root 

into  the  peridental  membrane.     The  radiograph  was 

made   several   weeks   after   patching  the   perforation   with   gutta-percha. 

There  is   scarcely  any  inflammation  at  all  at  the  point  of  perforation. 

showing  how  well  the  tissues  tolerate  gutta-percha. 

Under  this  heading  of  research  work  allow  me  to  mention  the  recent 


268  DENTAL  RADIOGRAPHV 

disturbing  paper  by  Dr.  William  Hunter,  of  London.  Let  me  say  that 
Dr.  Hunter's  charge  that  we,  as  a  profession,  practice  septic  dentistry  is 
well  founded.  One  needs  to  do  but  little  radiographic  work  to  be  fully 
convinced  that  the  conservative  dentistry  of  which  we  have  been  so  proud 
is  often  a  dreadful  mistake.  It  consists  all  too  often  of  simply  treating 
the  case  until  it  becomes  a  chronic  abscess,  then,  with  the  abatement  of 


Fig.    305.      The   arrow   points   to    a   perforation,    through    the   side   of    the    cuspid    root,    which    has 

been   patched   with   gutta-percha. 


the  acute  symptoms,  calling  the  case  cured.  As  a  radiographer,  a  man  in 
a  position  to  make  extensive  observations,  I  declare  that  the  root  canal 
work  of  the  majority  in  our  profession  is  a  menace  to  health.  Bad 
root  canal  work  is  not  usually  the  result  of  inability  to  do  the  work 
properly,  so  let  us  have  hope.  It  is  nearly  always  due  to  the  fact 
that  the  operator  thinks  he  cannot  get  paid  for  the  work.  And  it  is  indeed 
hard  to  convince  a  public,  which  has  received  its  dental  education  from 
advertising  quacks,  of  the  necessity  of  receiving  and  paying  for  the  proper 
treatment  of  its  teeth. 

I  would  not  be  understood  as  saying  that  I  agree  fully  with  Dr. 
Hunter.  I  do  not.  But  the  doctor  is  on  the  right  track.  He  knows  there 
is  such  a  thing  as  bad  dentistry,  septic  dentistry,  being  practiced,  as  do  all 
observing  men,  especially  radiographers. 

63.   m  a  Record  of  morK  Done. 

Any  sort  of  a  record  of  work  done  is  always  valuable.  Radiographic 
records  of  canal  fillings,  extractions  and  the  like  are  often  of  the  utmost 
value  to  the  operator.  Such  records  would  be  of  the  most  gratifying 
service  in  the  unpleasant  event  of  being  tried  for  malpractice.    A  patient, 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY     269 

let  us  say,  finds  it  necessary  to  go  to  the  hospital  for  a  week  after  the 
extraction  of  a  badly  impacted  third  molar.  The  next  thing  the  operator 
knows  is  that  suit  has  been  brought  against  him.  He  learns  that  he  "broke 
the  jaw-bone,"  and  that  the  patient  is  to  remain  a  "helpless  invalid  for 
the  balance  of  her  life,"  because  of  "his  lack  of  skill,  his  ignorance  and 
brutality."  Radiographs  of  the  case  showing  just  what  had  been  done 
for  the  patient  might  prevent  the  suit  or  win  the  case  for  the  operator. 

In  cases  where  the  patient  is  seized  with  a  decided  disinclination  to 
pay  a  dental  bill  the  radiograph  may  sometimes  be  used  to  advantage. 
These  patients  usually  suffer  from  the  loss  of  memory,  and  tell  the  judge 
that  the  plaintiff  is  quite  mistaken  in  imagining  that  he  filled  their  root 
canals.  Radiographs  would  go  far  toward  convincing  the  judge  of  the 
validity  of  the  claim. 

64.    Tn  eases  of  1)idden  Dental  Caries. 

The  "diagnosis  of  hidden  dental  caries  by  means  of  radiographs"  was 
suggested  and  recommended  by  Drs.  H.  W.  C.  and  C.  F.  Bodecker  in  a 
short  unillustrated  paper  printed  in  the  Dental  Review,  April,  1912.  I 
quote  a  paragraph  from  the  article  referred  to.  "The  diagnosis  of  caries 
in  its  first  stages  on  the  proximal  surfaces  of  molars  and  bicuspids  is 
often  difficult,  and  frequently  patients  complain  of  sensations  at  points 
where  we  cannot  discover  caries  either  with  floss  silk  or  explorer.  Sep- 
aration then  has  to  be  resorted  to,  in  order  to  definitely  locate  the  trouble. 
Sometimes  the  patient  is  not  able  to  point  out  any  single  tooth  in  which 
he  notices  the  sensation ;  he  simply  tells  us  that  it  is  'somewhere  on  that 
side,'  and  passes  the  finger  over  two  or  three  teeth.  Another  factor 
which  makes  diagnosis  difficult  is  reflex  pain.  Frequently  the  irritation 
is  in  an  upper  tooth,  and  the  patient  experiences  the  pain  in  a  lower  one, 
and  vice  versa.  Therefore,  to  obviate  the  useless  separation  of  teeth  in 
locating  small  carious  spots,  we  have  used  the  Roentgen  apparatus.  It 
would,  nevertheless,  be  a  useless  expenditure  of  time  and  work  to  radio- 
graph two  or  three  teeth  in  the  upper  arch,  and  if  no  defect  had  been 
found  to  repeat  the  same  in  the  lower.  We  have,  therefore,  constructed 
a  film  holder  by  the  aid  of  which  the  crowns  of  the  bicuspids  and  molars 
of  one  side  can  be  photographed  at  one  time." 

Personally,  I  have  never  put  the  radiograph  to  the  use  suggested  by 
the  Doctors  Bodecker,  but  it  is  my  intention  to  do  so. 

And  so — we  have  passed  over  the  uses  of  the  radiograph  in  the  prac- 
tice of  modern  dentistry,  and  it  has  been  a  long  trip.  Permit  me  to  repeat 
what  I  said  at  the  beginning  of  the  chapter,  for  you  are  now  better  able 
to  understand  and  believe  me.  Of  the  uses  for  the  radiograph  enu- 
merated, some  are  of  cases  that  the  general  practitioner  of  dentistry  may 


270  DENTAL  RADIOGRAPHY 

not  be  called  upon  to  diagnose  or  treat  oftener  than  once  or  twice  in  a 
lifetime,  perhaps  not  at  all;  but  by  far  the  greater  number  are  of  cases 
the  like  of  which  we  meet  almost  daily  in  the  practice  of  dentistry. 

There  is  a  popular  belief  among  dentists  at  large  that  the  use  of  the 
radiograph  is  indicated  only  in  the  baffling,  the  exceptional,  the  icono- 
clastic cases  in  our  practice.  This  is  not  true.  It  is  a  fact  that  the  radio- 
graph, in  a  spectacular  manner,  has  been  responsible  for  the  diagnosis 
and  cure  of  many  baffling  cases.  But  I  am  tempted  to^say  that  this  is 
unfortunate.  For  the  radiograph  does  not  always  solve  the  mysteries  of 
the  refractory  cases,  though  practitioners  of  dentistry  and  medicine  pay 
it  the  embarrassing  and  unfair  compliment  of  expecting  it  to  do  so.  The 
radiograph's  most  potent  value  in  dentistry  is  in  the  ordinary,  the  every- 
day cases  which  come  to  our  offices — in  cases  of  impacted  teeth  as  an  aid 
in  extraction ;  in  cases  where  the  apical  foramen  is  very  large  as  an  aid 
in  filling  the  canals  properly ;  in  cases  where  apical  sensitiveness  may  be 
due  to  a  large  apical  foramen  or  an  unremoved,  undevitalized  remnant  of 
pulpal  tissue;  in  cases  of  retained  temporary  teeth  to  learn  if  there  be 
succedaneous  teeth  present  in  the  jaw ;  in  cases  of  badly  decayed  teeth  of 
the  secondary  set  in  the  mouths  of  children  to  learn  if  the  roots  of  the 
diseased  teeth  are  fully  formed ;  in  cases  of  abscess  to  determine  which 
tooth  is  affected;  in  cases  of  traumatism,  and  so  on.  It  is  in  these  cases, 
met  constantly,  that  we  may  use  the  radiograph  and  derive  the  greatest 
assistance  and  benefit.  In  baffling  cases  we  will  often  be  disappointed  in 
our  use  of  the  radiograph,  but  in  the  ordinary  cases,  such  as  I  have  just 
enumerated,  never,  for  we  know  just  what  to  expect,  and  we  do  not  ex- 
pect too  much. 

It  should  ever  be  borne  in  mind  when  using  the  radiograph  for  diag- 
nostic purposes  that  it  is  only  an  aid;  in  many  cases  the  greatest  aid  we 
have,  but,  nevertheless,  only  an  aid  in  diagnosis.  No  other  methods  or 
means  of  diagnosis  should  be  forgotten  or  slighted. 

When  the  use  of  the  radiograph  fails  to  reveal  the  cause  of  the 
trouble  it  is  not  fair  to  look  upon  its  use  as  of  no  assistance  or  value.  For 
example,  a  patient  is  suffering  from  false  ankylosis.  Judging  from  the 
symptoms  we  suspect  an  impacted  lower  third  molar  to  be  the  active 
cause.  We  make  a  radiograph  and  fail  to  find  an  offending  third  molar 
or  anything  else  that  might  be  responsible  for  the  ankylosis.  It  is  natural 
that  we  should  be  disappointed,  but  we  must  not  feel  that  the  radiograph 
has  been  of  no  service  at  all,  for  we  now  know  that  an  impacted  third 
molar  is  not  the  cause  of  the  trouble,  and  we  have  taken  an  important 
step  in  diagnosis  by  elimination. 

In  printing  the  great  number  of  radiographs,  which  have  appeared  in 
this  chapter,  it  is  inevitable  that  some  should  not  be  good.     It  must  be 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY     271 

remembered,  too,  that  only  an  idea  of  what  can  be  seen  in  negatives  can 
be  learned  from  half-tones.  It  has  been  most  discouraging  to  the  writer 
to  observe,  at  times,  the  great  loss  of  detail  in  the  printed  half-tones,  as 
compared  to  the  original  negative.  However,  with  the  rarest  exception 
the  loss  of  detail  was  not  the  result  of  incompetency  on  the  part  of  the 
makers  of  the  half-tone  plates.    This  collection  of  dental  radiographs  has 


Fig.    306.      The   light   area   at   the   apex   of  the   upper   first   bicuspid  has   the   appearance    of    an 

abscess. 
Pig.   307.     The  same  case  as  Fig.  306,  proving  the  spot  at  the  apex  of  the   upper  first  bicuspid 

in  Fig.  306  is  not  an  abscess. 

been  transferred  from  the  photographic  print  to  the  half-tone  in  a  master- 
ful way,  and  its  failure  to  be  perfect  represents  only  the  shortcoming  of 
the  process  itself. 

Misinterpretation  of  radiographs  is  one  of  the  easiest  things  in  the 
world  and,  for  this  reason,  I  can  already  hear,  in  imagination,  the  cries 
of  condemnation  of  the  disappointed  ones  who  will,  within  the  next  few 
years,  take  up  dental  radiographic  work.*  I  believe  that  no  one  who  has 
ever  done  radiographic  work  has  experienced  disappointment  more  often, 
or  more  keenly,  than  I  have.  But  every  radiograph  ever  made  is  the 
product  of  simple  physical  and  chemical  laws,  and  when  misread  the 
fault  usually  lies  in  the  reader. 

Very  often  it  is  expedient  to  make  several  radiographs  of  the  same 
part,  changing  the  pose  slightly  to  verify  or  disprove  the  findings  in  the 
first  picture  of  the  part. 

Fig.  306  shows  what  seems  to  be  an  abscess  at 

figs.  306  and  307.  the  apex  of  an  upper  first  bicuspid.     Fig.  307  is  of 

the  same  case  and  shows  no  shadow  such  as  is  seen 

in  Fig.  306.    The  spot  in  Fig.  306  is  not  an  abscess ;  it  is  a  spot  produced 

by  faulty  technic  in  the  process  of  fixing. 


Written  in  1912. 


^72  DENTAL   RADIOGRAPHY 

When  I  started  this  chapter  I  expected  to  close  it  by  quoting  words 
of  praise  for  the  radiograph,  spoken  and  written  by  the  leading  men  in 
the  dental  profession.  I  shall  not  take  the  space  to  do  this,  but  shall  tell 
you  simply  that  I  could  if  I  wished.  I  shall  quote  but  one  man  who,  in 
an  impromptu  discussion,  voiced  the  sentiments  of  all.  Though  he  is  a 
specialist  in  oral  surgery,  he  speaks  as  well  for  the  orthodontist,  the  ex- 
tracting specialist  and  the  general  practitioner.  Dr.  T.  W.  Brophy  said 
"Now  that  we  have  the  X-ray  picture  to  help  us,  I  do  not  see  how  we 
could  possibly  get  along  without  it." 

The  greatest  argument  in  favor  of  the  use  and  value  of  the  radio- 
graph, however,  does  not  lie  in  the  enthusiastic  and  inspiring  remarks 
concerning  its  value,  but  in  the  irrefutable  facts  set  forth  and  illustrated 
in  this  chapter. 

Seldom,  indeed,  is  the  use  of  the  radiograph  in  dentistry  a  matter  of 
life  or  death  to  the  patient,  though  it  may  sometimes  be,  but  often,  often 
indeed,  does  health  and  happiness  depend  on  its  use.* 


*  In  the  light  of  recent  discoveries  pertaining  to  metastatic  infection  due  to 
local  foci  of  infection  in  the  mouth,  it  seems  that  the  use  of  the  dental  radiograph 
IS  often  a  matter  of  life  and  death.  One  needs  to  see  but  one  case  of  arthritis 
deformans  greatly  improved  or  cured,  following  the  eradication  of  oral  foci  of 
infection,  to  be  tremendously  impressed. 


CHAPTER  VIII. 

Che  Dangers  of  tbc  X-Kay. 

A  work  of  this  kind  would  be  worse  than  incomplete,  it  would  be  a 
positive  menace  to  the  welfare  of  the  public  and  the  profession,  without 
a  chapter  devoted  to  vigorous  warning  of  the  evil  results  that  may  occur 
from  exposure  to  the  X-rays. 

The  following  unfortunate  results  have  been  attributed  to  the  action 
of  the  X-rays:  dermatitis  {i.e.,  X-ray  burn),  cancer,  leukemia,  sterility, 
abortion,  insanity,  lassitude  and  alopecia. 

We  will  now  consider  each  of  these  foregoing  dangers,  taking  them 
up  in  the  order  named. 

X-ray  burns  are  of  two  kinds,  acute  dermatitis  and  chronic  derma- 
titis. 

Acute    dermatitis*    manifests    itself    anywhere 
JlCUtC  DeimatitiS.       from  twenty-four  hours  to  (in  rare  cases)  as  long  as 
two  or  three  months  after  exposure  to  the  rays.    The 
time,  however,  is  usually  from  three  to  fifteen  days. 

Itching  and  redness  are  the  first  symptoms  to  appear.  The  itching 
becomes  intense,  swelling  occurs,  the  skin  grows  harsh  and  dry,  and  has  a 
smooth,  glossy  appearance. 

In  mild  cases  the  inflammation  subsides  gradually  after  a  few  days 
and,  depending  on  the  severity  of  the  burn,  may  or  may  not  be  followed 
by  desquamation  and  loss  of  hair. 

This  Elberhart  calls  an  acute  dermatitis  of  the  first  degree. 

In  the  more  severe  form  of  acute  dermatitis,  termed  by  Elberhart  of 
the  second  degree,  there  will  be  the  formation  of  a  blister  with  the  usual 
serous  exudate  and  marked  neuralgic  pains. 


i^Elberhart  "Practical  X-Ray  Therapy." 

273 


274  DENTAL  RADIOGRAPHY 

In  the  very  severe  cases  of  acute  dermatitis,  where  the  deeper  layers 
of  the  skin  and  underlying  tissues  are  affected,  a  slough  forms  and  the 
destructive  condition  shows  a  marked  tendency  to  spread  and  become  ma- 
lignant.   Severe  pain  in  these  latter  cases  is  a  wellnigh  constant  symptom. 

After  exposing  himself  to  the  X-rays  a  great 

CbtoniC  Dermatitis,      number  of  times,  and  having  had  a  number  of  mild 

attacks  of  acute  dermatitis — or  perhaps  without  ever 


Fig.    308.     Chronic    X-ray    Dermatitis. 

having  had  acute  dermatitis — the  X-ray  operator  notices  certain  tissue 
changes  occurring,  usually  on  the  back  of  the  hands,  sometimes  on  the 
face  and  chest.  The  hands,  face  and  chest  are  most  likely  to  become  af- 
fected, because  these  parts  are  the  most  exposed  to  the  rays.  There  is  a 
pigmentation  of  the  skin  very  similar  to  tanning,  such  as  sun  and  wind 
will  produce.  Freckles  occur  in  some  cases.  The  skin  becomes  harsh,  dry 
and  wrinkled — the  same  changes  that  occur  with  age.  Hair  drops  out 
The  fingernails  become  brittle  and  thin  and  ridged  longitudinally.  Small, 
hard,  scabby  growths  (keratoses)  occur  here  and  there.  These  growths 
break  down  into  ulcers,  which  often  become  cancerous.    (Fig.  308.) 

There  has  been  a  great  deal  of  discussion  as  to 
Cancer.  whether  X-rays  can,  or  cannot,  produce  cancer,  but 

in  the  face  of  such  reports  as  Dr.  C.  A.  Porter's*  I 
do  not  see  how  anyone  can  dispute  it.  According  to  the  highest  author- 
ities. X-rays  can,  and  have,  produced  carcinoma.     In  1907  Dr.  Porter  re- 


*  "The    Surgical   Treatment   of   X-Ray    Carcinoma   and    Other    Severe    X-Ray 
Lesions,  Based  Upon  an  Analysis  of  Forty-seven   Cases." 


THE  DANGERS   OF    THE   X-RAY  275 

ported  eleven  cases  of  "unquestionable  X-ray  cancers,"  six  of  which 
proved  fatal. 

Cancer  usually  follows  a  chronic  dermatitis,  occurring  at  the  site  of 
a  former  ulcer,  though  it  may  result  from  a  very  severe  acute  dermatitis. 
When  caflcer  follows  chronic  dermatitis  the  victim  is  almost  invariably 
an  X-ray  operator ;  when  it  follows  acute  dermatitis  the  victim  is  usually 
a  patient  who  has  been  exposed  to  the  rays  for  therapeutic  purposes. 

Even  before  the  formation  of  cancer,  when  chronic  ulcers  appear, 
operation  after  operation  becomes  necessary.    These  operations  consist  of 


^ 


Fig.    309.      X-ra5'    Cancer. 

a  curettement  of  the  ulcer  and  skin  grafting.  With  the  formation  of  can- 
cer commences  amputation.  First  one  finger,  then  another,  then  two  more, 
then  a  liand,  both  hands,  an  arm.  A  welcome  death,  due  usually  to  the 
formation  of  metastatic  cancers  throughout  the  vital  organs  of  the  body, 
is  the  next  step  of  the  progressive  case. 

I  print  reports  here  by  Dr.  Porter  of  two  more  or  less  typical  cases 
of  fatality  due  to  X-ray  lesions : 

"Case  XXXI — Man,  32  years  old,  who,  after  three  years  of  X-ray 
work,  suffered  from  severe  lesions  on  both  arms,  breast,  neck  and  face. 
In  1901  there  began  a  slowly  growing  ulceration  of  the  back  of  the  right 
hand,  which,  by  the  middle  of  1902,  had  become  a  gangrenous  epithelioma ; 
glands  enlarged  at  the  elbow  and  in  the  axilla.  Amputation  at  the  shoul- 
der ;  axillary  glands  removed,  and  found  full  of  squamous-celled  car- 
cinoma. Sound  healing.  In  December,  1904,  a  typical  cancer  of  the  lower 
lip  and  another  of  the  angle  of  the  mouth  were  excised,  as  was  a  suspicious 


276 


DENTAL  RADIOGRAPHY 


lesion  on  the  back  of  the  left  hand.  In  March,  1905,  a  growth  of  the  cheek 
was  removed,  which  was  pronounced  by  Unna  to  be  a  sarcoma.  In  Sep- 
tember, 1905,  excision  of  the  right  lower  jaw  for  carcinoma.  Recurrence, 
involving  the  tongue  and  the  adjacent  cheek,  was  present  in  February, 
1906.     Death  soon  followed." 

"Case  XLVII.     Summary:    In   1897  began  work  with  the  X-rays, 
testing  the  tubes  for  several  hours  a  day.     First  noticed  erythema  and 


Fig.    310.      Hands    of    X-ray    operator    after    thirty    operations. 


warty  growths  in  1900.  In  1905,  keratoses  and  warts  had  formed  on  both 
hands,  chest  and  face.  First  carcinoma  developed  and  required  amputa- 
tion of  two  fingers  of  the  left  hand  in  April,  1907;  similar  growth  curetted 
on  right  hand.  By  March,  1908,  rapid  extension  of  the  disease  necessi- 
tating amputation  of  left  forearm  ;  curettage  of  epithelioma  on  right  hand. 
August,  1908,  involvement  of  epitrochlear  and  axillary  glands.  August 
II,  1908,  amputation  of  fingers  of  right  hand.  September  25,  1908,  ampu- 
tation at  shoulder.   Death  on  November  7,  1908;  general  carcinosis."    (Fig. 

309-) 

The  report  of  another  case  by  Porter  commences : 

"I  have  operated  upon  this  patient  under  ether  thirty-two  times,  the 
operations  varying  in  duration  from  one  hour  and  a  half  to  three  hours. 
At  present  there  remains  of  his  left  hand  two  joints  of  the  little  finger, 
the  forefinger  and  thumb ;  of  the  right  hand,  the  thumb,  the  middle  finger, 
barring  part  of  the  terminal  phalanx,  and  one  and  a  half  phalanges  of  the 
little  finger.  More  than  half  of  the  skin  of  the  backs  of  both  hands  con- 
sists of  Thiersch  grafts."     (Fig.  310.) 


Figs.  308,  309,  310,  copied  by  permission   from   The  Journal  of  Medical  Re- 
search. 


THE   DANGERS   OF    THE   X-RAY  277 

Regarding  the  pain  suffered  by  these  patients,  with  severe  chronic 
dermatitis  and  cancer,  Porter  says :  "The  amount  of  pain  suffered  is 
variable  though  usually  extreme.  From  my  experience  and  personal  com- 
munications with  patients,  I  believe  that  the  agony  of  inflamed  X-ray 
lesions  is  almost  unequaled  by  any  other  disease." 

Leukemia  is  a  blood  disease  characterized  by  an 
ECUkcmia.  increase   in  the  number  of   white  blood  cells.     The 

cardinal  symptoms  of  the  disease  are  insidious  ema- 
ciation and  lassitude.  It  is  generally  fatal.  Practically  nothing  is  known 
concerning  its  etiology.  It  is  suspected  that  continued  exposure  to  the 
X-rays  may  produce  leukemia  but,  as  yet,  this  supposition  has  not  been 
scientifically  substantiated. 

X-ray  operators  of  the  male  sex,  who  subject 
Sterility.  themselves  to  repeated  mild  exposures  to  the  rays, 

are  often  sterile.  This  sterility  is  due  either  to  the 
death  of  the  spermatozoa,  or  to  their  complete  disappearance  from  the 
semen.  This  condition  has  no  effect  one  way  or  the  other  on  the  carnal 
instincts  of  the  individual,  and  if  the  victim  will  discontinue  exposing  the 
parts  to  the  X-rays,  virility  will  be  regained.  Likewise  repeated  exposures 
of  the  ovaries  to  the  X-rays  will  produce  sterility  in  the  female  by  causing 
a  disappearance  of  the  Graafian  follicles ;  the  menses  do  not  cease,  and 
sexual  animation  remains  unaltered.  As  with  the  male,  the  power  of  re- 
production is  regained  promptly  when  the  parts  are  no  longer  subjected 
to  X-radiation. 

Quoting     from     Elberhart     (Practical     X-Ray 
Abortion.  Therapy)  :     "Fraenkel  claims  that  the  Roentgen  ray 

retards  the  growth  of  the  ovum  and  tends  to  produce 
abortion  when  the  thyroid  gland  and  ovaries  are  exposed  to  it." 

Fraenkel  has  in  mind  the  use  of  the  X-rays  as  a  therapeutic  agent, 
and  mentions  a  case  of  induced  abortion  after  twenty-five  exposures  of 
five  or  ten  minutes  each  every  other  day. 

For  the  slight  radiation  required  for  dental  radiographic  work  preg- 
nancy cannot  possibly  be  considered  a  contra-indication. 

There  is  a  somewhat  popular  superstition   that 
Tn$anity.  X-rays  will  produce  insanity  in  those  who  constantly 

expose  themselves  to  their  action.  This  belief  arose, 
I  think,  from  the  fact  that  a  prominent  X-ray  operator  lost  his  mind  a  few 
years  ago.  So  far  as  I  know  he  is  the  only  X-ray  operator,  of  the  thou- 
sands engaged  in  the  work,  who  has  met  with  such  a  misfortune,  and  it  is 
as  ridiculous  to  blame  the  X-rays  for  it  as  it  would  be  to  claim  that  his 
insanity  was  caused  by  the  suspenders  he  wore. 


278  DENTAL   RADIOGRAPHY 

There  is  a  belief  among  operators  themselves  that  X-ray  operators 
develop  a  "nervous,  restless,  intense  personality."  Whether  the  develop- 
ment of  such  a  personality  is  due  to  the  electric  condition  of  the  atmos- 
phere of  the  operating  room,  to  the  action  of  the  X-rays,  or  to  the  enthu- 
siastic interest  developed  by  research  work  is  a  matter  of  conjecture.  Per- 
sonally I  do  not  believe  any  of  these  things  are  responsible  for  the  restless, 
nervous  personality  of  so  many  operators  These  men  were  of  a  restless 
disposition  before  they  took  up  X-ray  work.  In  fact,  their  adoption  of 
the  work  was  but  a  sign  of  their  restlessness  and  desire  to  be  progressive. 

X-ray  operators  often  complain  of  a  feeling  of 
CassitUdC.  utter  exhaustion.    When  it  is  proven  that  X-rays  can 

produce  leukemia,  I  shall  believe  that  this  feeling  of 
extreme  lassitude  is  caused  by  exposure  to  the  X-rays.  Until  then  I  shall 
hold  to  the  belief  that  this  exhaustion,  which  unquestionably  does  occur, 
is  due  to  the  work,  physical  and  mental,  the  bad  air  of  the  dark  room,  and 
the  depressing  disappointments  experienced  by  all  conscientious  radi- 
ographers. 

Loss  of  hair  may  occur   from   a   severe  X-ray 
JllOPCCia.  burn,  but  I  can  find    no    reliable  authority  who  at- 

tempts to  prove  that  the  X-rays  will  produce  baldness 
of  the  head  without  dermatitis.* 

Knowing  now  the  dangers  of  the  X-rays,  how 

Protection.  shall  we  protect  ourselves  and  our  patients  against 

them?  We  shall  protect  ourselves  by  never  expos- 
ing any  part  of  our  bodies  to  the  direct  or  primary  X-rays,  and  our  pa- 
tients by  exposing  them  as  short  a  time  as  possible. 

How  can  we  do  radiographic  M^ork  without  exposing  ourselves  to 
the  X-rays  ? 

Sheet  lead  one-eighth  inch  thick  is  opaque  to  very  penetrating  X-rays. 
Lead  glass — a  transparent  glass  containing  a  great  deal  of  lead  silicate — 
though  it  would  need  to  be  "about  two  inches  thick  to  totally  obstruct  very 
penetrating  X-rays,"  nevertheless  ofifers  considerable,  and  perhaps  suf- 
ficient, protection  in  the  thickness  of  one-quarter  inch. 

The  writer  was  informed  that  linoleum  is  opaque  to  the  X-rays.  To 
test  the  verity  of  this  information  Figs.  311,  312  and  313  were  made.  A 
study  of  the  illustrations  will  show  that,  compared  to  lead  or  lead  glass, 
linoleum  ofifers  very  little  res'stance  to  the  rays;  compared  to  wood,  the 
resistance  is  much  greater.  White  linoleum  offers  more  resistance  than 
red,  green  or  bine. 

*  For  a  further  consideration  of  alopecia  see  Appendix,  Chapter  IX. 


THE  DANGERS   OF   THE   X-RAY 


279 


Fig.    311.     A,    B,   C,   and   D   are   pieces    of   linoleum.      E,   a   piece    of   sheet   lead    l-]6    inch    thick. 


Appliances  for 
Protection. 


The  appliances  which  may  be  used  for  protec- 
tion against  the  X-rays  are :     Protection  lead  screens 
(Figs.  314  and  315),  protection  lead  cabinets  (Figs. 
316  and  317),  protection  shields  for  the  tube  (Figs. 
60,  61.  63  and  64,  Chapter  III,  and  Fig.  318),  protection  or  safety  X-ray 
tubes   (Fig.  319),  X-ray  proof  gloves   (Fig.  320),  lead  glass  spectacles 
(Fig.  321),  and  protective  aprons. 


280 


DENTAL  RADIOGRAPHY 


Fig.    312.     A,   B,   C,   and   D,   same   as   in   Fig.    311.      E,   a   piece   of   lead   glass   1-4   inch   tliick. 


From  the  standpoint  of  protection  for  the  oper- 

ChC  Ecafl  Screen        ator  nothing  is  so  efficient  as  the  lead  screen  or  cabi- 

and  Cabinet.  net  (Figs.  314,  315.  316  and  317).     The  use  of  either 

makes  it  possible  for  the  operator  to  protect  himself 

completely  from  all  direct  X-rays. 

The  lead  used  in  protective  screens  and  cabinets  is  usually  one-six- 


THE  DANGERS   OF   THE   X-RAY 


281 


Fig.   313.     A,   B,  C,  and  D,  same  as  in  Fig!   311.     E,  the  dotted  lines  outline  the  position  of  a 
piece   of  pine  wood   1-2    inch   thick. 


teenth  inch  thick.  Lead  of  this  thickness  does  not  totally  obstruct  very 
penetrating  X-rays  when  the  tube  is  brought  close  up  to  it,  but  at  the 
usual  distance  of  several  feet  between  tube  and  screen  it  is  doubtful  if 
any  X-rays  penetrate  the  latter. 

The  lead  glass  used  in  the  windows  in  protection  screens  and  cabinets 
is  usually  one-fourth  inch  thick.     With  the  tube  placed  in  close  proximity 


2S2 


DENTAL   RADIOGRAPHY 


Fig.   314. 

Fig.    314.      Protective    lead    screen. 
Fig.    315.     Protective    lead    screen,    sectional    vievir. 


Fig.  315. 


THE   DANGERS   OF   THE   X-RAY 


283 


Fig.  31U.  Fig.    317 

Fig.    316.      Protective   lead   cabinet;    front   view. 
Fig.    317.     Protective   lead   cabinet;    rear   view. 


to  the  screen,  lead  glass  of  this  thickness  is  highly  translucent  to  the 
X-rays,  but  with  the  tube  a  distance  of  several  feet  the  rays  penetrate  the 
glass  but  feebly. 

Instead  of  the  lead  glass  window  a  screen  may  be  covered  entirely 
with  lead  and  mirrors  so  arranged  that  the  operator  may  observe  his  tube 
and  patient  from  his  position  back  of  the  screen. 

Let  it  be  clearlv  understood  that  the  man  standing  behind  a  lead 


284 


DENTAL  RADIOGRAPHY 


Fig.    318.     Protective   tube    shield   and   stand. 

screen  is  not  completely  protected  from  all  X-rays.  If  the  tube  is  rather 
close  to  the  screen  some  of  the  X-rays  may  penetrate  it — becoming  ex- 
tremely feeble,  however,  by  the  time  they  make  the  penetration — and  he 
is,  of  course,  exposed  to  the  secondary,  tertiary  and  other  sets  of  feeble 
rays  which  fill  the  room  like  light.  But  he  is  completely  protected  from 
the  powerful  dangerous  rays. 


THE  DANGERS   OF   THE   X-RAY  285 

The   protective    lead   screen,    or    cabinet,    or   their   equivalent,    is    a 
necessity  in  the  practice  of  modern  radiography. 

Protection  shields  are  of  three  varieties :  those 
Protection  made  of  lead  glass  (Figs.  60,  61  and  63,  Chapter  III), 

Shields.  those  depending  on  a  sheet  of  metallic  lead  for  their 

action  (Fig.  64,  Chapter  111),  and  those  made  of 
rubber  impregnated  with  lead  or  a  salt  of  lead  (in  appearance  similar  to 
Fig.  64).  The  X-ray  tube  fits  into  the  protection  shield,  which  latter  pro- 
tects the  patient  to  a  great  extent  against  the  action  of  all  X-rays  except 


Fig.    319.      Protection    or    safety.    X-ray    tube. 

those  which  pass  through  the  window  of  the  shield  and  are  being  used 
to  make  the  radiograph.  As  a  matter  of  fact,  the  patient  does  not  need 
this  protection  in  the  practice  of  dental  radiography,  but  it  is  not  inex- 
pedient to  use  even  protective  measures  that  are  thought  to  be  unneces- 
sary. The  operator  is  also  protected  in  a  degree  by  the  protective  shield. 
A  protection  shield  calculated  to  take  the  place  of  a  lead  screen  or 
cabinet  is  illustrated  in  Fig.  318.  The  protective  material  used  is,  I  judge 
from  its  appearance,  rubber  impregnated  with  lead  or  a  salt  of  lead.  The 
manufacturers  claim  to  use  a  German  preparation,  the  formula  of  which 
is  not  divulged.  This  material  is  more  opaque  to  the  X-ray  than  lead 
glass,  less  opaque  than  metallic  sheet  lead. 

Protection  or  safety  X-ray  tubes  are  manufac- 

ProtectiOtt  tured,  some  of  lead  glass  save  for  a  window  of  ordi- 

X-Ray  tubes.  nary  glass  transparent  to  the  X-rays,  and  some  with 

an  internal  protective  arrangement  which  allows  the 

X-rays  to  be  given  out  from  the  tube  from  a  limited  place  or  spot  only 

(Fig.  319). 


286 


DENTAL  RADIOGRAPHY 


The  hands  of  the  operator  may  be  protected  with 

Gloves.  X-ray  proof  gloves.     These  gloves  are  usually  made 

Tig.  320.  of  rubber  impregnated  with  lead  or  some  salt  of  lead. 

Protective  gloves  may  be  made  by  painting  ordinary 

leather  gloves  with  several  coats  of  white  lead.     X-ray  proof  or  "opaque" 

gloves,  as  they  are  called,  are  not  really  opaque  to  X-rays ;  they  are,  in 

fact,  quite  translucent  to  powerfully  penetrating  rays. 

Gloves  should  be  used  when  the  operator  finds  it  necessary  to  hold 
the  film  in  the  patient's  mouth  himself.     Seldom,  very  seldom  indeed,  is 


^^•^1 M  nifi  iaiUi'i 


Fig.   320.  Fig.   331. 

Fig.    320.     X-ray    proof,    opaque,    or    protection    gloves. 

Fig.    321.     Lead   glass    spectacles. 

it  necessary  for  the  operator  to  do  this,  and  I  warn  you  against  the  practice 
with  the  same  feeling  that  I  would  cry  "Don't !"  if  I  should  see  you  mak- 
ing a  plaything  of  a  culture  of  the  bacillus  of  the  white  plague. 

Protection  lead  glass  spectacles  may  be  used  to 

Spectacles.  protect  the  eyes   (Fig.  321).     Not  because  the  eyes 

are  any  more  susceptible  to  the  ill  effects  of  the  X- 

rays  than  the  skin  of  the  face,  but  because  injury  to  them  is  such  a  serious 

matter.       Operators  suffering  from  chronic  dermatitis  of  the  face  usually 

sufifer  also  impairment' of  vision. 

Protection   aprons   of   lead-impregnated    rubber 
Protection  niay  be  purchased  from  manufacturers  of  X-ray  sup- 

Hpron.  plies.    They  are  used  to  prevent  sterility. 

Protection  gloves,  spectacles  and  aprons  are  ob- 
viously not  needed  so  long  as  the  operator  remains  behind  a  screen. 

Having  now  told  you  of  the  dangers  of  the  X- 
€fficieitcy  of  I'^ys  and  shown  what  measures  have  been  adopted. 

Protective  measures,  to  prevent  disaster,  the  question  arises,  Have  these 
modern  means  of  protection  proved  efficient? 
So  far  as  I  know,  no  man  who  has  conscientiously  and  consistently 
stayed  behind  a  protective  lead  screen,  or  in  a  lead  cabinet,  has  developed 
eithe^-  cancer  or  dermatitis  or  sterility,  or  sufifered  or  experienced  any 
other  pathological  change  which  could  be  attributed  to  the  X-rays.  And 
some  have  been  engaged  in  the  work  for  as  long  as  twelve  years. 


THE   DANGERS   OF    THE   X-RAY  287 

The  severe  and  fatal  cases  of  dermatitis  and  cancer  have  occurred 
in  patients  who  received  prolonged  and  repeated  X-ray  treatments 
for  some  disease,  and  in  pioneer  operators. 

As  practitioners  of  dental  radiography,  we  will  never  be  called  upon 
to  make  such  exposures  of  our  patients  as  are  necessary  when  the  X-rays 
are  used  as  a  therapeutic  agent. 

The  pioneer  operators  whose  lives  were  ruined  and  destroyed  by  the 
X-rays  did  not  protect  themselves  at  all,  not  knowing  that  it  was  neces- 
sary. Even  without  any  protection  disaster  did  not  manifest  itself  imme- 
diately, as  might  be  imagined.  Men  worked  for  months  and  even  years 
before  any  trouble  developed.  Take  the  case  of  a  well-known  manu- 
facturer of  X-ray  tubes,  for  example.  He  exposed  himself  two  or  three 
hours  daily,  six  days  in  the  week,  for  a  little  over  a  year  before  he  no- 
ticed any  dermatitis.  It  must  be  remembered,  however,  that  at  that  time 
the  machines  and  tubes  could  not  generate  near  the  same  number  of  X- 
rays  that  the  improved  machines  and  tubes  of  to-day  can,  and  the  danger, 
was  therefore  less.     . 

As  an  example  of  how  efficient  even  slight  protec- 

€fficicncy  of  tion  is.  Dr.  Porter  cites  a  case  of  dermatitis  of  the 

Slight  Protection.        hands,  save  for  the  skin  protected  by  a  broad  gold 
ring,    which    remained    perfectly    normal.     The    im- 
munity which  even  light  clothing  offers  is  shown  by  the  rarity  or  slight 
degrees  of  dermatitis  above  the  cuffs,  or  on  the  other  parts  of  the  body 
protected  by  clothing. 

Before  it  was  known  to  be  dangerous,  operators  formed  the  habit 
of  using  their  hands  for  penetrometers — observing  them  through  the  flu- 
oroscope  to  learn  the  power  of  penetration  of  the  X-rays.  This  prac- 
tice has  doubtless  caused  many  cases  of  dermatitis  and  cancer  of  the  back 
of  the  hands.  The  use  of  any  penetrometer  save  those  of  an  improved 
type  which  enable  the  operator  to  "look  around  a  corner"  necessitates  the 
exposure  of  the  operator,  especially  his  hands,  to  the  rays,  and  I  object 
to  their  use  for  this  reason. 

Summarizing  the  danger  to  the  operator,  we  may 
Summarv  ^^^  simply  this :    If  he  will  observe  strictly  the  rule 

Of  Danger  to  remain  behind  a  lead  screen  or  in  a  lead  cabinet 

to  Operator.  he  may  work  for  a  period  of  ten  or  twelve  years  in 

safety.  What  the  dangers  of  exceeding  this  time 
limit  are  we  do  not  know.  Perhaps  there  are  none.  Perhaps  all  the  older 
X-ray  operators  will  die  of  leukemia  within  the  next  ten  years.  Who 
can  say?  We  are  entitled  to  our  opinions,  but  no  one  really  know^s.  The 
pioneers  in  the  work  are  still  in  danger ;  we  who  follow  are  comparatively 
safe. 


288  DENTAL   RADIOGRAPHY 

Though  the  operator  need  never  expose  any  part  of  his  body  to  any 
except  the  weak,  harmless  X-rays  which  fill  the  room,  it  is  necessary  to 
expose  at  least  that  part  of  the  patient  being  radiographed  to  the  direct 
rays.  The  question  arises,  how  long  may  we  expose  the  patient  with 
perfect  safety,  without  any  danger  whatever  of  producing  acute  derma- , 
titis  ?     Authorities  are  very  reluctant  to  set  this  time  limit. 

The  very  few  cases  of  serious  acute  dermatitis  due  to  exposure  for 
radiographic  work  occurred  when  the  outfits  used  were  so  small  that  the 
time  for  exposures  was  as  long  as  20  or  30  minutes.  Compare  such  ex- 
posures with  those  of  to-day,  which  range  from  a  fraction  of  a  second  to 
only  one  minute  at  most,  even  with  the  small  suitcase  outfits,  and  the  im- 
probability of  producing  dermatitis  will  be  appreciated. 

The  first  rule  regarding  the  exposure  of  patients  should  be,  never  ex- 
pose the  patient  longer  than  absolutely  necessary. 

And  now  I  shall  place  myself  in  line  for  criti- 
CilllC  Citllit  for  cism  by  authorities,  by  setting  a  time  limit  of  ex- 

6xpO$ind  Patients.*  posure  of  the  patient.  Even  with  the  smallest  appa- 
ratus, and  where  a  number  of  exposures  are  neces- 
sary, the  aggregate  time  of  exposure  need  not  and  should  not  exceed  two 
minutes.  If  it  is  necessary  to  use  this  full  time,  two  minutes  in  one  day, 
then  do  not  expose  the  same  part  of  the  same  patient  for  about  14  to  30 
days.  Give  the  skin  a  chance  to  recover  from  any  change  produced  in 
it,  and  so  guard  against  a  cumulative  efifect  of  the  X-rays.  I  cannot  im- 
agine a  case  in  dental  radiography  which  would  require  an  exposure  longer 
than  two  minutes.  And  seldom,  indeed,  will  it  be  found  necessary  to 
expose  the  patient,  even  in  the  aggregate  when  several  radiographs  are 
made,  as  long  as  the  time  limit  set. 

Two  minutes  is  a  conservative  time  limit  if  the  X-ray  machine  in  use 
does  not  force  more  than  about  20  milliamperes  through  the  X-ray  tube, 
and  if  the  distance  between  target  and  skin  at  the  time  of  exposure  is  not 
less  than  16  inches. 

It  may  be  truthfully  stated  that,  so  far  as  the  patient  is  concerned, 
the  application  of  the  X-rays  in  the  practice  of  radiodontia,  is  attended 
with  no  danger,  if  the  operator  is  careful. 

"In  the  early  days  of  the  X-rays  there  was  a  tendency  to  attribute  X-ray 
burns,  not  to  the  X-rays  themselves,  but  to  some  accompanying  factor,  the 

*  For  a  further,  more  scientific  and  more  comprehensive  consideration  of  the 
subject  of  the  exposure  of  patients  to  the  X-rays  see  the  appendix  to  Chapter  VIII. 


THE  DANGERS   OF    THE   X-RAY  289 

exclusion  of  which  would  prevent  the  occurrence  of  X-ray  burns."*  Thus  it 
was  suggested  that  burns  were  due  to  an  electrical  condition  surrounding 
the  tube ;  to  chemical  conditions  surrounding  the  tube ;  to  bacteria  being 
carried  into  the  tissues  by  the  X-rays ;  to  violet  rays,  and  so  on.  It  is  gen- 
erally conceded  to-day,  however,  that  X-ray  burns  are  the  result  of  a  spe- 
cific action  of  the  X-rays  themselves  on  the  tissues. 

Zhi  TiltCt,  There  is  a  popular  theory  that   for  X-rays  to 

have  an  efifect  on  the  skin  they  must  be  absorbed  by 
it.  Thus,  the  more  penetrating  X-rays  which  pass 
completely  through  the  derma  are  less  likely  to  produce  dermatitis  than 
rays  of  less  penetration — just  enough  penetration  to  be  absorbed.  Know- 
ing this  theory  we  will  now  consider  the  use  of  a  filter. 

First,  however,  let  us  dwell  on  some  points  which  were  not  touched 
upon  in  Chapter  III,  when  we  discussed  the  generation  and  nature  of 
X-rays.  It  was  stated  in  Chapter  III  that  the  X-rays  from  a  tube  of  high 
vacuum  were  the  most  penetrating — that  the  penetration  of  the  X-rays 
varied  directly  according  to  the  degree  of  vacuum  of  the  tube.  Thus  the 
X-rays  from  a  high  vacuum  tube  are  very  penetrating,  the  rays  from  a 
medium  vacuum  tube  of  medium  penetration,  and  the  rays  from  a  tube 
of  low  vacuum,  of  low  penetration.  While  this  is  true,  there  is  something 
further  to  be  said.  Take  the  high  vacuum  tube :  while  most  of  the  di- 
rect X-rays  given  ofif  from  it  are  of  high  penetration,  some  rays  of  me- 
dium and  low  penetration  are  also  generated.  While  the  tube  of  medium 
vacuum  generates  X-rays  of  medium  penetration  principally,  some  rays 
of  high  and  low  penetration  are  also  generated ;  and  though  the  X-rays 
from  a  tube  of  low  vacuum  are  by  far  mostly  of  low  penetration,  some  few 
rays  of  medium  and  high  penetration  are  given  ofif  also. 

Since  the  tube  of  a  high  vacuum  is  the  one  we  use  in  radiographic 
work,  let  us  enumerate  the  different  sets  of  X-rays  given  off  from  such  a 
tube.  First,  are  the  direct  rays  of  high  penetration — these  are  by  far 
the  most  numerous ;  next,  the  sets  of  direct  X-rays  of  medium  and  low 
penetration — these  are  comparatively  few  in  number ;  then  secondary  X- 
rays  given  off  from  the  glass  of  the  tube ;  and  last,  if  there  is  any  in- 
verse current  in  the  tube,  the  rays  generated  by  it. 

If  now  the  theory  of  absorption  for  effect  is  correct,  then  it  is  de- 
sirable to  expose  the  patient  only  to  the  direct  penetrating  X-rays,  and  not 
to  any  of  a  less  penetrating  nature.  In  an  effort  to  gain  this  end  the 
filter  is  used. 

Filters  are  made  of  wood,  aluminum,  leather  and  various  other  ma- 
terials.    For  example,  a  piece  of  sole  leather  (no  definite  thickness)    is 


*Pusley  and   Caldwell,  "Roentgen  Rays  in   Therapeutics  and  Diagnosis: 


290  DENTAL   RADIOGRAPHY 

placed  over  the  window  of  the  tube  shield.  The  X-rays  from  the  tube 
pass  through  it  before  striking  the  patient  and  the  leather  filters  out,  ab- 
sorbs, all  ( ?)  of  the  weaker  rays,  which  might  otherwise  be  absorbed  by 
the  skin,  and  so  guards  against  dermatitis. 

The  danger  of  producing  dermatitis  varies  directly  according  to  the 
number  of  X-rays  which  strike  the  part.  Recollect  that  X-rays  emanate 
from  a  point,  traveling  in  diverging  lines.  Thus  the  greater  the  distance  be- 
tween the  target  and  the  skin  the  fewer  rays  strike  the  latter  and  the  less 
danger  of  dermatitis.  When  the  tube  is  brought  very  close  (within  three 
or  four  inches)  to  the  part  and  no  filter  is  used  the  skin  is  then  acted  upon 
not  only  by  a  much  greater  number  of  the  direct  penetrating  rays,  but  also 
by  the  softer  direct  rays  and  by  the  secondary  rays  from  the  glass  of  the 
tube,  so  increasing  the  danger  of  burning  materially.  Thus  it  will  be  seen 
that  the  use  of  the  filter  permits  the  operator  to  place  the  tube  close  to  the 
patient,  so  that  his  film  or  plate  is  within  range  of  a  greater  number  of 
penetrating  direct  rays,  and  at  the  same  time  protects  the  patient  against 
the  soft  rays. 

Theoretically,  the  use  of  the  filter  should  aid  in  obtaining  a  clear 
radiograph  by  cutting  out  all  save  the  direct  penetrating  rays.  It  is  not 
as  efficient  in  this  respect,  however,  as  the  compression  cone  or  cylinder 
and  diaphragm.     (Fig.  65.) 

The  number  of  direct  X-rays  generated  by  a  given  tube  varies  di- 
rectly according  to  the  number  of  milliamperes  sent  through  it.  Thus 
danger  of  dermatitis  also  varies  directly  according  to  the  number  of  mil- 
liamperes sent  through  the  tube.  To  elucidate :  the  distance  between  the 
tube  and  the  skin  remaining  the  same,  an  exposure  of  one  minute  with 
ten  milliamperes  passing  through  the  tube  will  have  practically  the  same 
physiologic  efifect  as  an  exposure  of  two  minutes  with  five  milliamperes 
passing  through  the  tube. 

There  is  no  such  thing  known  as  either  acquired 

Immunity.  or    natural    immunity  to  the  action  of  the  X-rays. 

Some  are  more  susceptible  than  others,  but  no  one 

is  immune.     Blondes  are  reputed  to  be  more  susceptible  than  brunettes. 

One  burn  greatly  predisposes  to  another. 

The  careful  practitioner  of  dental  radiography. 
treatment  Of  unless  he  meets  a  case  of  idiosyncrasy,  will  never 

Hcute  X-Kay  have  occasion  to  make  use  of  knowledge  regarding 

Dermatitis.  the  treatment  of  acute  X-ray  dermatitis.     It  is  well, 

however,  to  have  the  knowledge  even  though  we  are 
never  called  upon  to  use  it.  The  most  important  thing  to  know  concern- 
ing the  treatment  of  acute  X-ray  burns  may  be  learned  from  the  nursery 


THE  DANGERS  OF  THE  X-RAY  .291 

rhyme  about  "Little  Bo-Peep"  and  "her  sheep.''  ''Eet  them  alone."  So 
many  drugs  aggravate  the  condition  that  their  use  is  contraindicated.  A 
normal  salt  solution  is,  perhaps,  the  best  wash  and  may  be  used  freely. 

There  will  be  men  in  our  profession  who  will  not  take  up  radiographic 
work,  and  who  will  say  as  an  excuse  for  not  doing  so  that  they  believe 
the  work  "too  dangerous."  Men  who  give  this  excuse  are  either  unac- 
quainted with  the  facts  relative  to  the  real  danger  or  they  are  deceiving 
themselves.  A  disinclination  to  do  necessary  work,  mental  and  physical, 
may  lead  a  man  to  believe  that  the  reason  he  does  not  take  up  X-ray  work 
is  because  he  believes  it  to  be  "dangerous." 

It  is  interesting  to  know  that  the  rays  given  off 
Radium  by  the  recently  discovered  element  radium  are  very 

Rays.  similar  to  the  X-rays. 

The  commercial,  so-called,  radium  is  not  pure 
radium.  It  is  a  salt  of  radium,  usually  radium  bromid.  So  far,  radium 
never  has  been  isolated.     Radium  bromid  is  a  white  crystal. 

"In  1896  it  was  discovered  that  the  metal  uranium  gave  off  rays  very 
similar  to  X-rays.  Observing  that  different  pieces  of  uranium  varied 
greatly  in  their  radio-activity,  M.  and  Mme.  Curie,  of  Paris,  working  on 
the  hypothesis  that  uranium  itself  was  not  radio-active  at  all,  but  derived 
this  property  from  some  impurity  incorporated  in  it,  isolated  radium 
bromid  from  the  metal  uranium."* 

At  present  radium  salts  are  obtained  from  uranium  oxid,  which  lat- 
ter is  first  obtained  from  pitchblende,  a  heavy  black  material  in  appearance 
somewhat  similar  to  anthracite  coal.  One  ton  of  pitchblende  must  be 
treated  with  approximately  five  tons  of  various  chemicals  and  fifty  tons 
of  water  to  obtain  one  gram  of  radium  bromid.  The  present  markel  price 
of  one  gram  of  radium  bromid  ranges  from  $1,500  to  $125,000,  according 
to  the  radio-activity  of  the  salt. 

Radium  rays,  like  X-rays,  travel  in  straight  lines,  and  secondary 
rays  are  given  off  from  objects  which  they  strike.  They  pene- 
trate objects  directly  according  to  the  density  of  the  object, 
ai'xd  act  on  a  photographic  plate  like  light  and  X-rays.  Their 
physiologic  effect  on  the  skin  is  very  similar  to  X-rays.  They  pro- 
duce a  dermatitis  almost  identical  to  X-ray  dermatitis.  Becquerel  carried 
a  sealed  glass  tube  containing  0.2  gram  of  radium  salt  in  his  shirt  pocket 
for  six  hours.  Fifteen  days  thereafter  a  dermatitis  closely  simulating 
X-ray  dermatitis  appeared,  then  subsided  in  about  thirty  days.  One  case 
of  fatality  from  leukemia  caused,  presumably,  by  radium  has  been  re- 
ported. 


*Tousey,  "Medical  Electricity  and  Roentgen  Rays." 


CHAPTER  IX. 
Purcbasina  a  Kadiograpbic  Outfit 

Before  considering  the  purchase  of  a  radiographic  outfit,  let  us  con- 
sider the  question  of  who  should  do  dental  radiographic  work.  Should  it 
he  done  by  specialists  or  the  general  practitioners  of  dentistry  ?  Six  years 
ago  it  was  my  habit  to  answer  this  question  unhesitatingly,  and  say  "  by 
the  specialist." 

My  reasons  for  believing  that  dental  radiographic  work  should  be 
done  by  specialists  were:  (i)  I  was  of  the  opinion  that  the  radiograph 
was  not  particularly  useful  in  the  practice  of  dentistry  except  in  rare 
cases,  and  (2)  there  being  no  text-book  on  the  subject,  proper  self-educa- 
tion in  the  art  was  difficult,  almost  to  the  point  of  being  impossible. 

As  I  see  the  situation  to-day,  however,  the  use  of 

CbC  0ity  the  radiograph  is  indicated  in  so  many  cases  that  it 

Practitioner.  would  be  rather  impractical  for  the  general  practi- 

tioner to  refer  all  radiographic  cases  to  the  special- 
ist, unless  said  general  practitioner  of  dentistry  happened  to  be  located 
in  a  city  of  sufficient  size  to  support  a  radiodontist ;  not  simply  a  specialist 
in  radiography,  but  a  specialist  in  dental  radiography.  And  this  would  be 
practical  only  if  the  radiodontist  did  work  at  practical  fees  and  could  be 
depended  upon  to  faithfully  fill  all  appointments.  But  granting  the  pres- 
ence of  such  a  radiodontist  in  a  city  it  would  be  advantageous  for  the 
general  practitioner  of  dentistry  to  patronize  him  and  thereby  give  his 
patients  the  benefit  of  better  service  than  he  himself  could  hope  to  give. 
Also  the  trained  radiodontist  is  in  a  position  not  only  to  give  better  serv- 
ice, but  to  give  that  service  at  a  more  reasonable  fee. 

Each  general  practitioner  who  installs  an  X-ray  outfit  must,  if  he 
wishes  to  be  fair  to  himself,  charge  a  fee  in  proportion  to  the  money,  time 
and  study  invested.  Suppose  now  one  hundred  practitioners  install  X- 
ray  machines  :  The  investment  in  money,  time  and  study — for  all  of  which 
the  "ultimate  consumer,"  the  patient,  must  pay — becomes  tremendous 
compared  with  the  investment  of  a  single  man,  a  radiodontist,  who  could 
serve  these  one  hundred  dentists.  Thus  it  will  be  seen  that  the  new  spe- 
cialist, the  radiodontist,  has  a  right  to  existence,  looking  at  the  matter 

202 


PURCHASING    A    RADIOGRAPHIC    OUTFIT  293 

from  an  economic  standpoint.  And  from  the  standpoint  of  service  there 
can  be  no  fair  comparison  of  the  skilled  specialist  to  the  general  practi- 
tioner. A  study  of  Appendix  Chapter  VI  will  give  some  idea  of  the 
treachery  of  radiographs  in  the  hands  of  men  who  do  not  know  their  lim- 
itations. Fewer  radiographs  with  intelligent  interpretations  is  infinitely 
better  than  many  radiographs  incorrectly  interpreted. 

Ihe  argument  advanced  in  favor  of  each  dentist 

Jlraument  doing  his  own  radiographic  work  is  that  it  is  so  much 

J!gain$t  Referring  more  convenient,  for  pulp  canal  work,  to  have  the 

Patients.  machine  accessible  and  in  the  same  office  at  all  times. 

The  convenience  of  having  a  machine  in  the  office  is 
indisputable,  but  the  inconvenience  of  getting  it  there,  and  using  it  in- 
telligently after  it  is  there,  is  likewise  indisputable.  The  dentist  who 
refers  his  patients  to  a  radiodontist  for  canal  work  should  not  make  it 
his  practice  to  place  a  wire  in  the  canal  of  a  tooth,  send  the  patient  to  a 
specialist,  located  a  mile  away  perhaps,  then  wait  for  the  patient  to  return 
with  a  radiographic  report.  The  patient  should  be  referred  to  the  radio- 
dontist between  the  usual  sittings.  (A  medicinal  dressing  may  be  sealed 
in  the  canals  with  the  wires.) 

Whether  the  city  man,  who  has  access  to  a  radiodontist  should  do 
at  least  some  of  the  simpler  radiographic  work,  referring  the  balance  to 
the  specialist,  depends  on  whether  he  has  the  time  and  enthusiasm  neces- 
sary to  take  up  the  work.  Unless  he  has  the  time  to  do  it  as  it  should  be 
done,  and  unless  the  nature  of  the  work  appeals  to  him,  he  had  better  not 
attempt  it. 

But  how  about  the  dentist  practicing  in  a  small 

Country  city  or  town,  who  does  not  have  access  to  a  radio- 

Practitioner.  dontist?     The  dentists  of  such  a  community  should 

band  together  and  select  one  of  their  number  to  do 
radiographic  work,  buy  a  good  outfit,  and  refer  patients  to  the  man 
selected  to  do  the  work.  In  case  the  dentists  of  the  smaller  communities 
cannot  or  will  not  do  this,  then  each  man  must  have  his  own  X-ray  outfit 
and  do  the  best  he  can,  just  as  the  country  practitioner  is  compelled  to  do 
the  best  he  can  with  cases  of  malformations  of  the  dental  arch,  difficult 
extractions,  pyorrhea  and  other  things  which  he  could  refer  to  the  spe- 
cialist if  he  were  located  in  a  city. 

I  have  said  that  fewer  radiographs  with  intelligent  interpretations 
of  them  is  better  than  a  greater  number  with  less  intelligent  interpreta- 
tions. I  must  add  that  radiographs  and  interpretations  of  any  sort  are 
better  than  no  radiographs  at  all,  and,  as  I  make  this  statement,  I  have 
not  forgotten  the  perfectly  asinine  things  which  may  be  done  as  a  result 
of  misinterpretation  of  radiographs. 


294  DENTAL   RADIOGRAPHY 

For  extensive  diagnostic  examination  with  the 
Specialists'  X-rays,  requiring  the  making  of  many  radiographs, 

lUorli.  some  extra-orally,  the  work  should  as  a  rule  be  done 

by  a  radiodontist,  even  though  it  necessitates  travel- 
ing from  town  to  city  on  the  part  of  the  patient. 

The  foregoing  is  a  consideration  of  what  I  think  should  be  done. 
What  will  actually  happen  is,  I  think,  that  most  dentists  will  install  X- 
ray  machines.  The  majority  will  do  poor  work  and  will  not  know  it  is 
poor  and  so  will  continue  the  work,  while  others  who  have  access  to  radio- 
dontists,  seeing  their  own  limitations,  will  discard  their  machines.  The 
country  practitioner,  even  though  he  detest  the  work  and  recognizes  his 
inability  to  do  it  well,  will  probably  be  forced  to  continue  it,  and  so  in 
time  will  develop  proficiency. 

My  second  reason  for  having  formerly  been  of  the  opinion  that  all 
radiographic  work  should  be  referred  to  specialists — viz.,  the  difficulty  of 
self-education — I  hope  is  no  longer  a  good  reason,  for  I  have  tried,  in  this 
work,  to  supply  a  text-book  which  will  enable  the  man  who  wishes  to 
take  up  dental  radiography  to  do  so  without  wasting  a  great  deal  of  time 
and  energy  reading  books  on  electricity,  photography  and  general  X-ray 
work. 

Some  manufacturers  make  such  statements  re- 
ilntrutbfUl  garding     radiographic     work     as,     "The     work     is 

Statements.  extremely  simple  and  can  be  mastered  in  a  few  min- 

utes ;  in  the  time  it  will  take  to  glance  over  our  in- 
structions which  we  send  with  each  outfit."  As  a  result  of  such  misrepre- 
sentation men  have  taken  up  the  work  in  profound  ignorance  and  so  have 
endangered  their  own  and  their  patient's  health  and  life.  Self-education 
to  do  the  simplest  work  intelligently,  safely  and  well  is  not,  I  assure  you, 
a  matter  of  a  few  minutes'  study,  but  of  many,  many  hours. 

In  passing  let  me  mention  X-rays  as  a  therapeu- 
X-Kavs  as  a  ^^^  agent  in  dentistry,  and  condemn  them  as  useless. 

tbetapeutiC  It  is  so  difficult  to  measure  the  dose  in  X-radiation 

flaent.  that  it  is  only  by  long  and  usually  soul-trying  and  dis- 

astrous experience  that  a  man  becomes  competent  to 
use  X-rays  as  a  therapeutic  agent.  The  work  should  be  done  by  special- 
ists only.  General  practitioners  of  either  dentistry  or  medicine  are  liable 
to  do  more  harm  than  good  when  attempting  therapeutic  X-radiation. 

X-rays  have  been  employed  in  the  treatment  of  pyorrhea  alveolaris, 
but  no  results  have  been  obtained  that  have  not  been  gained  by  the  use 
of  the  easier-used,  better-known,  less-dangerous  drugs,  commonly  ap- 
plied. The  incurable  cases  remain  incurable,  whether  the  X-rays  are 
nsed  or  not,  and,  in  the  cases  in  which  disease  is  due  to  local  irritants 


PURCHASING    A    RADIOGRAPHIC    OUTFIT  295 

which  can  be  removed,  recovery  takes  place  as  a  result  of  the  universally 
known  methods  of  treatment — again,  whether  the  X-rays  are  used  or 
not.  X-rays  are  used  also  for  treatment  of  cancer  of  the  mouth  and 
leukoplakia,  but  such  diseases  are  comparatively  rare,  and,  if  treated  with 
the  X-rays,  the  work  should  be  done  by  specialists.  As  far  as  I  know, 
this  is  the  extent  of  the  therapeutic  application  of  the  X-rays  to  diseases 
of  the  mouth — an  extremely  limited  application. 

In  short,  my  opinion  of  the  value  of  the  X-rays  in  the  practice  of 
dentistry  is  this :  As  a  means  of  making  dental  radiographs  they  are  in- 
valuable ;  as  a  therapeutic  agent,  they  are  worse  than  useless. 

Of  what  should  a  dental  radiographic  outfit  con- 

ReauirementS  of  ^^^^  ^     Naming  the  bare  necessities  for  the  simplest 

an  X-Ray  work — to  which  the  operator  may  add,  as  he  does 

Outfit.  the  work  and  feels  the  need  of  expediting  apparatus 

— we    have  :    ( i )    Photographic   paraphernalia    and 

supplies,  including  a  dark-room  lantern,  trays,  a  glass  graduate,  prepared 

developing  powder  or  solution,  prepared  fixing  powder,  and  films;   (2) 

an  X-ray  machine  or  coil;  (3)  an  X-ray  tube;  (4)  a  tube-stand;  (5)  a 

lead  screen;  (6)  a  lead.  X-ray-proof  box  for  films  and  plates. 

All  the  photographic  paraphernalia  and  supplies  may  be  purchased 
at  any  photographic  or  X-ray  supply  house.  The  expenditures  for  pho- 
tographic paraphernalia  and  supplies  need  not  exceed  $5. 

There  are  three  kinds  of  X-ray  machines  for  the  prospective  buyer 
to  choose  from;  the  transformer  or  interrupterless  coil  (Figs.  15  and  38), 
the  induction  coil  (Fig.  13),  and  the  high  frequency  coil  (Fig.  14).  The 
so-called  "  dental  X-ray  machines  "  are  either  small  transformers,  me- 
dium-sized induction  coils  or  large  high-frequency  coils. 

The   transformers   are  the   most  powerful   and 
TtttcrfUptCI*lC$$  most    expensive    X-ray    machines    on    the    market. 

Coils.  Transformers  range  in   size   from  the  small  dental 

transformer,  selling  at  about  $300  or  $400,  to  the  very 
large  transformers,  such  as  those  used  by  specialists  and  found  in  hos- 
pitals, selling  at  over  a  thousand  dollars. 

With  transformers,  intra-oral  radiographs  may  be  made  in  exposures 
ranging  from  a  fraction  of  a  second  to  about  5  seconds  ;  extra-oral  radio- 
graphs from  a  fraction  of  a  second  to  about  10  seconds. 

Transformers  operate  with  equal  reliability  on  either  a  D.  C.  or 
A.  C.  circuit.  Take  two  transformers  of  an  equal  efficiency,  one  for  a 
D.  C.  circuit  and  one  for  an  A.  C.  circuit,  however,  and  the  machine  for 
the  D.  C.  circuit  will  be  a  larger,  more  expensive  machine  than  the  one 
for  the  A.  C.  circuit  owing  to  the  difference  in  construction.  (See  Fig. 
38.) 


296  DENTAL   RADIOGRAPHY 

Induction  coils  are  made  in  various  sizes.     The 
Induction  largest   ones   rival   the   transformers    in   power,   the 

0OllS.  smaller  ones  are  not  nearly  so  powerful.     Induction 

coils  range  in  price  from  about  $200  to  $600. 
With  induction  coils   intra-oral   radiographs   may  be  made   in  ex- 
posures ranging  from  a  fraction  of  a  second  to  about  15  or  20  seconds; 
extra-oral  radiographs  from  about  i  or  2  seconds  to  about  45  seconds. 
Induction  coils  operate  at  their  highest  efficiency  on  the  D.C.  circuit. 
Most  high-frequency,   suitcase,  X-ray  coils  are 
I)l3b-Trcqucncy  built  to  sell ;  not  to  make  radiographs.    Only  the  most 

tKoilS.  powerful  of  the  type  are  capable  of  doing  good  den- 

tal radiographic  v/ork.     I  would  advise  the  prospec- 
tive purchaser  to  insist  on  a  practical  demonstration  before  investing. 

With  high-frequency  coils  which  are  strong  enough  to  be  used  for 
dental  X-ray  work,  intra-oral  radiographs  may  be  made  in  from  about 
3  to  30  seconds ;  extra-oral  radiographs  from  about  12  seconds  to  a  length 
of  time  so  great  that  the  making  of  extra-oral  radiographs  becomes  im- 
practical. 

High-frequency  machines  operate  at  their  highest  efficiency  on  the 
A.C.  circuit. 

The  high-frequency  X-ray  coils  range  in  price  from  about  $150  to 

$200. 

A  d  or  7-inch  X-ray  tube  is  the  proper  size  to  do 
dental  radiographic  work.     The  price  of  the  6  or  7- 
X-Ray-tUbC$  \nz\\  tube  is  well  standardized,  and  is  from  $20  to 

$35-    When  purchasing  a  new  X-ray  tube  for  dental 
work  take  care  not  to  get  one  which  necessitates  vacuum  regulation — i.  e., 
vacuum  reduction — to  keep  it  from  backing  up  5  inches  of  parallel  spark. 
The  Coolidge  tube  costs  $125,  and  necessitates  the  purchase  of  a  spe- 
cial controlling  apparatus  at  a  cost  of  about  $200. 

There  is  a  great  variety  of  tube-stands  to  choose 
from   (Figs.  59,  60  and  61).     They  range  in  price 
Cube-Stands  ^^^^  ^^^  ^^  ^^^^_    ^-^e  small  tube-stands  or  holders 

which  are  fastened  on  to  the  suitcase  coils  do  not  per- 
mit of  a  sufficient  range  of  movement  to  adjust  the  tube  properly,  nor 
are  they  substantial  enough  to  hold  the  tube  firmly  immovable. 

Lead  screens  (Figs.  314  and  315)  cost  from  $10 
Protection  to  $30.     Even  the  best  lead  screens  are  not  backed 

Screens  with  lead  thicker  than  1-16  inch.     The  writer  oper- 

ates back  of  a  "home-made"  screen,  the  lead  of 
which  is  yi  inch  thick,  and  the  3  x  3  inch  window  the  lead  glass  of  which 
is  i^  inches  thick.     The  material  for  this  screen  cost  $15.     It  is  not  a 


PURCHASING    A    RADIOGRAPHIC    OUTFIT  297 

particularly  beautiful  piece  of  furniture,  and  if  the  time  spent  in  building 
it  be  considered  worth  anything,  I  did  not  save  money,  but  the  finished 
screen  offers  more  protection  than  any  I  know  of  on  the  market. 

An  X-ray-proof  box  (Fig.  115)  may  rightfully 
A-Kay-rrOOT  ^^  considered  a  necessity;  for  all  photographic  films, 

plates  and  paper  must  be  kept  in  such  a  box  or  in 
another  part  of  the  building  away  from  the  lighted  X-ray  tube.  Obviously 
it  is  impractical  to  keep  the  photographic  films,  plates  and  paper  any  great 
distance  from  the  X-ray  apparatus.  Hence  such  a  box  becomes  a  neces- 
sity.   X-ray-proof  boxes  cost  from  $5  to  $20. 

A  man  may  figure  from  the  foregoing  approximately  what  it  will 
cost  him  to  buy  the  kind  of  an  outfit  he  wishes  to  purchase. 

The  following  is,  to  the  best  of  the  writer's  recollection,  a  complete 
list  of  the  manufacturers  of  X-ray  apparatus  in  America:  The  Victor 
Electric  Co.,  Chicago;  the  Scheidel- Western  X-Ray  Coil  Co.,  Chicago; 
the  American  X-Ray  Equipment  Co.,  New  York  City;  the  Edwards  In- 
strument Co.,  Indianapolis ;  the  Kelly-Koett  Mfg.  Co.,  Covington,  Ky. ; 
the  Wm.  Meyer  Co.,  Chicago;  the  Wappler  Mfg.  Co.,  New  York  City; 
the  Kny-Scheerer  Co.,  New  York  City ;  the  Campbell  Electric  Co.,  Lynn, 
Mass. ;  the  Vulcan  Coil  Co.,  Los  Angeles ;  the  H.  G.  Fischer  &  Co.,  Chi- 
cago ;  Noyes  Bros.  &  Cutler,  Inc.,  St.  Paul ;  Geo.  W.  Brady  &  Co.,  plate 
manufacturers,  Chicago;  Roentgen  Mfg.  Co.,  Philadelphia;  Green  & 
Bauer  Tube  Co.,  Hartford,  Conn. ;  MacAlaster-Wiggins  Tube  Co.,  Chi- 
cago ;  Machlett  &  Son,  tube  manufacturers,  Chicago ;  Mcintosh  Battery 
&  Optical  Co.,  Chicago  ;  Kesselring  X-Ray  Tube  Co.,  Chicago ;  the  Rogers 
Electric  Laboratories  Co.,  Cleveland,  Ohio ;  the  Eastman  Kodak  Co., 
Rochester,  N.  Y. ;  the  Cramer  Dry  Plate  Co.,  St.  Louis,  Mo. ;  Snook 
Roentgen  Mfg.  Co.,  Philadelphia,  Pa.;  Waite  &  Bartlett  Co.,  New  York 
Citv;  Columbia  X-Ray  &  Electric  Corporation,  New  York  C\\^. 


CHAPTER  X. 

Stereoscopic  Kadiograpby. 

The  word  stereoscopic  is  derived  from  two  Greek  words,  meaning 
'solid"  and  "to  see." 


Fig.   322.      Hand  stereoscope   in   u.se. 

The  phenomenon  of  the  stereoscopic  picture  or  radiograph  is  one 
very  difficult  to  explain  briefly.  It  is  sufficient  for  us  to  say  here  that  to 
gain  a  stereoscopic  effect — that  is,  to  get  a  picture  rich  in  perspective — 
we  must  have  two  pictures,  one  for  each  eye,  and  observe  them  with  a 
stereoscope  (Figs.  322  and  323).  When  the  two  pictures  are  properly 
focused  in  the  stereoscope,  the  observer  no  longer  sees  two  flat  pictures 
of  the  same  object,  but,  instead,  the  single  object  stands  out  in  clear 
perspective,  just  as  it  would  if  we  looked  at  the  object  itself,  the  two 
pictures  being  registered  on  the  retina  of  either  eye  and  the  merging  centre 
of  the  brain  fusing  them  into  one. 


298 


STEREOSCOPIC  RADIOGRAPHY 


299 


To  make  stereophotographs  it  is  necessary  to  use  a  special,  double- 
lens  camera  (Fig.  324),  which  takes  a  picture  for  each  eye  simultaneously. 
Figs.  337  and  338  are  stereophotographs. 

A  moment's  consideration  of  the  subject  makes  it  obvious  that  two 
radiographs,  one  for  each  eye,  cannot  be  made  simultaneously.     We  must 


Fig.    323.     Large   stereoscope    made   especially    for    observing   stereoradiographs 


place  the  X-ray  tube  in  the  position  to  make  the  radiograph  for  one  eye 
and  make  the  exposure,  then  shift  the  tube  two  and  one-half  inches  (the 
approximate  distance  between  the  eyes),  place  a  new  plate  or  film  in 
exactly  the  same  position  occupied  by  the  first  plate  or  film  (and  this 
without  changing  the  position  of  the  part  being  radiographed),  and  make 
a  second  exposure  to  get  the  radiograph  for  the  other  eye. 

To  accomplish  the  proper  shifting  of  the  tube  a 

Stereoscopic  special  tube  stand  or  pedestal  should  be  used.   There 

Cube  Stand.  are    several    such   stands    on   the   market   known    as 

"stereoscopic  tube  stands."     The  one  shown  in  Fig. 

61,  and  again  in  Figs.  326  and  330,  is  used  by  the  writer. 


300 


DENTAL   RADIOGRAPHY 


To   accomplish   the   removal  of   the   first  plate 
PIjiI^  after  exposure,  and  replace  it  with  a  second  plate 

0b(ingci*$.  for   the    second    radiograph,    without    changing   the 

position  of  the  part  being  radiographed,  it  is  neces- 
sary to  use  a  plate  changer  (Fig.  325),  or  a  "stereoscopic  table"   (Fig. 


Fig.    324.      Double   lens   camera    for   making   stereophotographs. 


Fig.   325.      Piatt   changer. 


326),  which  latter  is  simply  a  large  plate  changer  made  into  a  table.  The 
principle  of  all  plate  changers  is  the  same.  The  part  being  radiographed 
rests  undisturbed  on  a  window  of  celluloid  or  thin  aluminum,  while  the 
plates  slide  beneath  in  a  tunnel. 


STEREOSCOPIC  RADIOGRAPHY 


."^oi 


.^^"*^**^ 


)T 


Fig.    326.     Stereoscopic   table    and    tube   stand.      H,    centering   rod. 


The  plate  changer  illustrated  in  Fig.  330,  and  explained  by  diagram  in 
Fig.  327,  differs  from  others  in  that  only  one  five  by  seven  inch  plate 
is  used,  two  pictures,  five  by  three  and  one-half  inches,  being  made  on 
either  end  of  the  plate.  A  five  by  seven  stereoradiograph  (both  pictures 
on  the  one  plate)  may  be  observed  with  a  hand  stereoscope  (Fig.  322), 
while  all  other  plate  stereoradiographs  must  be  observed  with  the  special 
stereoscope  (Fig.  323). 


3C2 


DENTAL   RADIOGRAPHY 
I  J 


Fig.  327.  A  and  AA,  lead  which  protects  the  plate  against  the  action  of  the  X-ray.  B,  window 
of  thin  aluminum  or  celluloid  on  which  the  part  being  radiographed  lies.  C,  end  of  the  tunnel. 
D,  plate  carrier.  E,  end  of  5x7  plate  on  which  the  first  radiograph  is  made  with  the  tube  in 
position  I.  EE,  end  of  plate  on  which  second  radiograph  is  made  after  it  is  shifted  under 
the  window   B,  and  the  tube  is  in  position  J.     F,   centering  line.      G,   angle   of  X-rays  with  the 

tube   in  the  first  position,   I.      H,   angle   of   X-rays   with   the  tube   in  second  position,  J. 

The   diagram   shows   the   tube  being   shifted    on   a   line   with   its   long   axis.      It   may   be   shifted   in 

this    manner,    or    at    any    angle    to    its    long    axis — it    makes    no    difference. 


Fig.   .328.      Compression  cones,  cylinder  and  square,   and  diaphragms  for  same. 


STEREOSCOPIC  RADIOGRAPHY  303 

tecbnic  for  makins  Stercoradiograpbs. 

Let  us  now  take  a  concrete  example  and  describe  and  discuss  the 
steps  taken  in  the  making  of  Fig.  339. 

First,  what  should  be  the  distance  between  the 
Distance.  target  and  the  plate?     There  are  no  special  rules  to 

follow  regulating  the  distance  between  the  target  and 
the  plate  when  making  stereoradiographs.  The  same  results  were  ob- 
tained by  the  writer  with  the  distance  twelve  inches  as  when  working 
at  twenty-four  inches. 


Fig.    329.      The    lead    glass    bowl    and    X-ray    tube    must   be    removed    while    the    centering    rod    is 
being  used.      When   the   stand   is   "set,"   the    rod   is    removed   and   the   protection    bowl   and    X-ray 

tube    replaced. 

The  first  step  is  to  "centre  the  tube,"  to  place  it 

Setting  so  that  a  line  (line  F  of  Fig.  327)  drawn  from  the 

Cube  Stand.  focal  point  on  the  target  will  strike  the  plate  in  the 

center.    This  may  be  done  with  the  greatest  accuracy 

by  the  use  of  the  centering  rod   (Fig.  326),  but  the  use  of  the  rod  is 

not  imperative  unless  a  compression  cone  or  cylinder  (Fig.  328)  is  to  be 

used,  as  will  be  described  presently. 

After  centering  the  tube,  when  using  a  stand  like  the  one  in  Figs. 
326  and  330,  the  stand  is  "set"  so  that  the  tube  may  be  moved  one  and 
one-quarter  inch  on  each  side  of  the  center  to  positions  I  and  J  of 
Fig.  327  (see  illustration). 


304 


DENTAL   RADIOGRAPHY 


Fig.    330.      Pose    for    making    Fig.    344.      It    is    often    expedient   to    have    the    patient    remove    the 

coat   and    collar   for   this    pose. 


STEREOSCOPIC  RADIOGRAPHY 


305 


wmmmmmmmmmmmmmmmm^ 


Fig.    331.      Modified   Kny-Sheerer   film    holder. 


Fig.   333.      The  film   holder  shown   in   Fig.    331    in   position. 


Fig.    333.      Another   view    of    the   film   holder   in    positic 


3o6 


DENTAL   RADIOGRAPHY 


.  It  is  not  necessary  to  tip  the  tube,  as  it  is  shifted, 

tipping  in  order  to  have  the  X-rays  strike  the  object  and 

tI)C  Cube.  plate  at  the  proper  angles — at  the  angles  at  which  the 

eyes  of  an  observer  would  see  the  object,  because  the 

X-rays  emanate  from  the  focal  point  on  the  target  in  diverging  lines  in  all 

directions.     So  the  same  X-rays  are  not  used  to  make  the  second  picture 

that  are  used  to  make  the  first.     If  they  were,  it  would  be  necessary  to 

tip  the  tube  to  make  them  strike  the  object  and  the  plate  at  the  proper 

angles.     (Observe  lines  G  and  H  of  Fig.  327,)     When  using  a  compres- 


Fig.   334  Fig.   335  Fig.   336 

Fig.    334.      The    photographic    print    from    which    this    halftone    was    taken    was    made    from    the 

original  negative,   or   "first   picture." 
Fig.    335.      The    same    as    Fig.    334,    except    made    from    "pictures    one    and   two,"    held    together 

with    binding    strips. 
Fig.   336.     The  same  field  as    Fig.    334,   but   made   from   the   "third   picture." 

sion  cone  or  cylinder  we  do  use  the  same  rays  tO'  make  both  radiographs, 
and  hence  it  becomes  necessary  to  tip  the  tube  as  it  is  shifted.  This  can 
be  accomplished  with  accuracy  only  by  the  use  of  the  centering  rod  (see 
Fig.  329).  Thus,  if  a  cone  or  cylinder  is  to  be  used,  the  tube  stand  must 
be  "set"  not  only  to  shift  the  tube  but  to  tip  it  also  as  it  is  shifted. 

With  the  tube  stand  "set,"  the  tube  in  position  I  of  Fig.  327,  and  the 
plate  in  the  position  shown  in  Fig.  327,  the  first  exposure  is  made.  The 
tube  is  then  shifted  to  position  J,  the  plate  carrier  pushed  in  until  the 
unexposed  half  of  the  plate  comes  under  the  window  B,  and  the  second 
exposure  is  made.  Since  the  two  radiographs  are  made  on  the  same  plate 
in  this  instance,  special  care  should  be  taken  to  expose  them  each  the 
same  length  of  time.  Otherwise  they  will  "come  up"  unequally  in  the 
developing  solution  and  radiographs  of  different  densities  will  result. 

If  the  technic  outlined  above  is  followed,  it  will  be  found  when 
observing  the  finished  stereoradiograph  that  we  see  the  part  from 
the  position  of  the  tube  during  exposure.  Thus  observe  Fig.  339,  which 
was  taken  with  the  palm  of  the  hand  toward  the  plate,  a  coin  on  the 
back  of  the  hand,  a  needle  under  the  hand. 

If,  instead  of  following  the  technic  as  given,  the  first  exposure  be 
made  with  the  tube  in  position  J  and  the  plate  as  shown  in  Fig.  327, 
and  the  second  exposure  with  the  tube  in  position  I',  after  the  plate  is 
shifted;   then,    when   observing   the    finished    stereoradiograph,    it    is    as 


STEREOSCOPIC  RADIOGRAPHY 


307 


Fig.    337.       Stcix-oiihotograiih    of    the    skull    of    a    monkey,    frc 

skulls    of    vertebrates. 


Dr.    John    J,    Kyle's    collection    of 


though   we   saw    the   part    from    the   position    of    the    plate    during    its 
exposure  (see  Fig.  340). 

This  changing  of  position  of  observation  may  be  accomplished  also 
by  interchanging  the  two  radiographs — placing  the  right  on  the  left  and 
the  left  on  the  right.  Take  Fig.  339,  for  example ;  interchange  the  radio- 
graphs and  the  stereoradiograph  is  the  same  as  Fig.  340;  or  take  Fig. 
340  and  interchange  the  radiographs  and  the  stereoradiograph  is  the  same 
as  Fig.  339.  The  interchanging  of  radiographs  must  be  done  without 
inverting  them,  or  the  change  of  position  of  observation  will  not  be  ac- 
complished— the  stereoscopic  effect  will  remain  the  same  and  the  part  will 
simply  be  viewed  upside  down. 


Fig.    338. 


Sagittal    section    of    the    skull    of    a    monkey,    from    Dr.    John    J. 
skulls    of   vertebrates. 


Kyle's    collection    of 


308 


DENTAL   RADIOGRAPHY 


Fig.    339.      Showing   tlie   coin   on    one   side   of   tlie   hand,   the    needle    on    the    other,      ilere   we   ob- 
serve   the    hand    from    the    position    of    the    tube. 


Fig.  340.     The  same  as  Fig.  339  except  that  we  observe  the  hand  from  the  position  of  the  plate 
during  its  exposure,  instead  of  the  position   of  the   X-ray  tube. 


STEREOSCOPIC  RADIOGRAFHY 


309 


Fig.    341.     Three    nails    of    the    same    size    and    length.     One    is    in    a    vertical    position,    the    other 
two   lean   toward   the    observer,    at   different   angles. 

Figs.  341,  342  and  343  are  the  same  radiographs  mounted  differently. 
No  stereoscopic  effect  at  all  is  seen  in  Fig.  343,  because  the  tube  was 
shifted  at  right  angles  to  the  long  axis  of  the  nails.  Had  the  tube  been 
shifted  on  a  line  with  the  long  axis  of  the  nails  it  would  l:ie  necessary  to 
observe  them  as  in  Fig.  343  to  get  a  stereoscopic  effect. 


Fig.    342.      The   same   as    Fig.    341    except    that    the    individual    radiographs    are    interchanged,    the 

right    changed    to   the    left   sid'e    and    the    left    to   the    right    side.      Thus    in    this    stereoradiograph 

the    leaning    nails    lean    away    from    instead    of   toward    the    observer. 


310 


DENTAL   RADIOGRAPHY 


Fig.  343.     Xo  stereoscopic  effect  at  all  is  obtained  with  the   radiographs  mounted  as  in  this  figure. 


Special  Cecbnic 

for  Dental  Stereo- 

Radlograpby. 


\Y&  now  come  to  a  more  definite  consideration 
of  dental  stereoscopic  radiography.  Stereoradio- 
graphs  of  the  lower  teeth  may  be  made  on  plates 
using  the  plate  changer  illustrated  in  Fig.  327.  Fig. 
344  is  such  a  stereoradiograph.     Fig.  344  was  made 


from  the  pose  illustrated  in  Fig.  330. 


Fig.    341.     Though   the   stereoscopic   effect  is   not   very   good   the'  figure   is    representative    of   what 
can   be   done   by   the   method   employed   to   make   this   stereoradiograph. 


STEREOSCOPIC  RADIOGRAPHY  311 

When  making  stereoradiographs  on  separate  plates,  like  Figs.  345 
and  346,  it  is  necessary  to  use  a  large  plate  changer,  like  Figs.  325  and  326. 
Figs.  345  and  346  were  made  on  eight  by  ten  inch  plates,  and  the  radio- 
graphs reduced,  as  shown  in  the  figures,  so  that  they  might  be  observed 
with  the  small  hand  stereoscope.  To  observe  the  original  negatives  it  is 
necessary  to  use  a  large  stereoscope  (Fig.  323). 

When  making  dental  stereoradiographs,  on  films 
Dental  Tllm  held  in  the  mouth  during  their  exposure,  the  problem 

l)Older.  of  replacing  the  first  film,  after  its  exposure,  with  a 

second  film,  which  will  occupy  precisely  the  same 
position  as  the  first,  is  one  fraught  with  great  difficulties.  In  an  effort 
to  accomplish  this  the  writer  uses  a  Kny-Sheerer  film  holder  and  model- 
ing composition.  The  film  holder,  as  I  use  it,  is  modified  almost  beyond 
recognition  (see  Figs.  331,  332  and  333).  Films  may  be  placed  in  this 
modified  holder  in  exactly  the  same  position,  and,  by  the  aid  of  the  im- 
pression of  the  occlusal  surfaces  of  the  teeth  in  modeling  composition, 
the  holder  may  be  replaced  in  the  mouth  in  the  same  position.  This  film 
holder  is  applicable  to  practically  any  part  of  the  mouth,  but  especially 
so  to  the  molar  region. 

It  is  not  absolutely  necessary,  but  I  prefer  to  have  the  patients  pose 
in  a  recumbent  position  for  all  dental  stereoscopic  work,  believing  they  are 
less  likely  to  move  the  head  while  the  films  are  being  changed  in  this 
position  than  they  would  be  if  sitting  in  a  chair.  Thus  the  pose  for 
making  Fig.  347  was  a  slight  modification  only  of  Fig.  330. 

Thanks  to  the  work  of  Dr.  C.  Edmund  Kells,  we  now  know  that  it 
is  not  necessary  to  have  the  two  films  in  exactly  the  same  position  to  make 
a  stereoradiograph  like  Fig.  348.  All  that  is  necessary  is  to  have  them 
occupy  exactly  the  same  plane.  Hence  no  film  holder  need  be  used.  The 
film  is  placed  in  the  month  as  in  Figs.  95,  96  and  103. 

After  the  two  film  negatives  are  made,   prints 
PrevaratiOll  of         "^^^  ^^  made  from  them,  and  these  prints  mounted  on 
KadioarapbS  for        cardboard  to  be  observed  with  the  hand  stereoscope. 
Study  Witb  stereoscope.   Or  the  negatives  themselves  may  be  observed  stereo- 
scopically  by   mounting  them   on   transparent  glass, 
sticking  them  in  place  with  binding  strips  such  as  are  used  in  passe  par- 
tout  work. 

The  distance  between  the  radiographs  mounted  for  stereoscopic  ob- 
servation should  be  approximately  two  and  one-half  inches  from  a  given 
point  in  one  radiograph  to  the  same  point  in  the  other  radiograph.    Great 


312 


DENTAL   RADIOGRAPHY 


Fig.   345.     Antero-posterior  view  of  a  dry  skull.     The  right  sphenoid  sinus  is  filled  with  lead  shot 

accuracy   in    mounting    the    radiographs    for    stereoscopic    study    is    not 
necessary  though  preferable. 

It    is    always  .  expedient    when    making    dental 
CandnttirkS.  stereoradiographs  to  place  some  landmark,  such  as 

an  anchor  clamp  band  or  a  wire,  on  the  teeth.  Know- 
ing then  that  the  screw  and  nut  of  the  clamp  band  are  on  the  lingual  or 
buccal  side,  as  the  case  may  be,  or  that  the  wire  is  twisted  on  the  lingual 
or  labial  side,  as  the  case  might  be,  we  may  determine  immediately,  when 


Fig.  346.     The  reproduction  here  has  lost  much  of  its  excellence.      When  the   original   negatives 

were  viewed  in  the  illuminating  stereoscope,  one  could  look  as  clearly  and  directly  into  the  skull 

as -he  could  into  a  soap  bubble.     The  dark  outline  is  the  antrum  nearer  the   observer  filled  with 

lead  shot.      (Stereoradiograph  by  A.   M.    Cole   and   Raper.) 


STEREOSCOPIC  RADIOGRAPHY 


313 


observing  the  stereoradiograph,  whether  we  observe  the  part   from  the 
position  of  the  tube  or  the  position  of  the  film. 

Dr.  Kells  states  that,  as  a  general  proposition,  a  more  perfect  stereo- 
scopic effect  may  be  gained  if  the  radiographs  are  mounted  so  that  the 
stereoradiograph  is  observed  from  the  position  of  the  film.  This  is  true, 
and  one  reason  for  it  is  that,  other  things  being  equal,  the  closer  an  object 


Fig.    347.      Impacted   lower,   left,   third   molar,    viewed   from   the    lingual, 
the   clamp   band   are   on   the    lingnal. 


The   screw  and    nut   of 


Fig.    348.      Viewed   from  the  position   of   the   film — from   the   lingual.      The    temporary    cuspid   is 

so   much   decayed  and   resorbed  it  can  scarcely   be   seen.     The   wire   around   its   neck   can   be   seen 

clearly.      The    wire    is    twisted    on    the    labial. 

is  to  the  plate  or  film  the  clearer  it  is  outlined  in  the  radiograph.  Like- 
wise as  we  look  upon  a  scene,  the  closer  objects  are  clearer  than  those  at 
a  distance.  Hence,  when  we  observe  a  stereoradiograph  from  the  position 
of  the  film  or  plate  during  its  exposure,  those  parts  of  the  stereoradio- 
graph seeming  to  be  closer  to  us  are  clearer,  while  those  farther  away  are 
less  clear. 

If  the  film  packets  used  contain  two  films  each,  four  negatives  will 
be  made,  and  these  may  be  mounted  on  clear  glass,  so  that  the  operator 


314 


DENTAL  RADIOGRAPHY 


may  observe  the  part  from  the  position  of  the  film  and  tube  also. 

In  direct  proportion  as  things  are  large  or  small 
it  is  easy  or  difficult  to  discern  perspective.  The 
parts  in  dental  radiographs  are  so  small  that  it  is 
difficult  to  gain  perspective.  In  an  effort  to  over- 
come this  handicap,  to  an  extent  at  least,  Fig.  350 

was  made.    Fig.  350  is  an  enlargement  of  Fig.  349.    Owing  to  the  loss  of 


enlarsement 

of  Dental 

Stcreoradiograpbs. 


Fig.   345'.     Impacted  upper,  third  molar,  viewed   from  the  position   of  the   tube.     The   wire  pass- 
ing around  the   neck  of  the   second   molar   is   twisted    on   the   lingual.     The   impacted   tooth   sets 

to   the   buccal. 


Fig.    350.      Same    as    Fig.    349    enlarged. 

detail  incident  to  enlargement  there  seems  little  if  any  advantage  in  this 
step.  There  is  none  made  at  the  present  time,  but  a  magnifying  stereo- 
scope would  probably  be  of  value  for  viewing  dental  stereoradiographs. 

So  much  for  the  technic  involved  in  the  practice 

Practical  Ualue        °^  dental  stereoscopic  radiography.    Let  us  now  con- 

Of  Dental  Stereo-        sider  the   results,   the   practical   application   and  the 

radioarapbl.  possibilities     of     dental     stereoscopic     radiography. 

Frankly,  the  results  are  discouraging.     Considering 


STEREOSCOPIC  RADIOGRAPHY 


315 


the  difficulties  of  practice,  and  the  results  obtained  at  the  present  time, 
there  is  an  extremely  limited  practical  application  of  the  stereoradiograph 
to  dentistry.  What  the  future  possibilities  of  dental  stereoscopic  radiog- 
raphy are  I  would  not  attempt  to  say.  My  hope  is  that  some  day  we 
may  be  able  to  stereoradiograph  the  upper  molar  roots  successfully. 

By  describing  it  I  think  I  have  proved  that  the  technic  involved  to 
do  dental  stereoscopic  work  is  so  difficult  that  the  work  should  be  left 
entirely  to  specialists  in  radiography.  Even  in  the  hands  of  the  most 
skillful  it  seems,  at  the  present  time,  that  there  are  several  good  reasons 
why  it  will  never  be  popular.     The  reasons  are:     (i)  The  difficulty,  and 


Fig.    351.      Coins   at   different   distances   from    a   wire   screen. 


at  the  same  time  the  necessity,  of  obtaining  two  radiographs  uniformly 
rich  in  detail.  (2)  The  difficulty  and  necessity  of  placing  two  films  in 
the  mouth  in  the  same  position.  (3)  The  difficulty  and  necessity  of  having 
the  patient  maintain  the  same  pose  while  the  two  exposures  are  made. 
(4)  The  great  amount  of  time  consumed  to  do  the  work.  (5)  The  parts 
being  so  small  makes  it  especially  difficult  to  gain  a  stereoscopic — a  per- 
spective— effect.  (6)  One  of  the  most  important  reasons  why  dental 
stereoscopic  work  probably  never  will  be  popular,  even  among  specialists, 
is  that  we  feel  no  great  need  of  it.  The  single  radiograph  is  not  totally 
lacking  in  perspective,  and  a  careful  study  of  it  will  reveal  almost,  if  not 
quite,  as  much  as  can  be  seen  in  the  dental  stereoradiograph.  (7)  The 
stereoradiograph  is  sometimes  misleading.  For  example,  see  Fig.  351. 
To  make  this  illustration  three  coins  were  placed  on  a  piece  of  wire 
screening,  one  directly  against  the  screen,  the  other  two  resting  on  cotton 


3i6 


DENTAL   RADIOGRAPHY 


built  up  to  hold  them  at  different  distances  from  the  screen.  In  the 
stereoradiograph  the  coin  which  rests  against  the  screen  seems  to  stand 
out  from  it  a  short  distance. 

Some  day  perhaps  we  may  so  modify  and  perfect  our  technic  that 
the  stereoradiograph  will  be  of  indispensable  value  (i)  in  observing  the 
three  roots  of  upper  molars;  (2)  in  seeing  a  wire  passing  through  a 
perforation  to  the  labial,  buccal  or  lingual;  (3)  in  some  particular  cases 


Fig.    352.      Same    as    Fig.    339    made    "plastic. 


of  impacted  teeth  to  show  more  exactly  their  location,  and  so  aid  in  the 
extraction;  (4)  in  showing  the  orthodontist  when  he  may  move  the  com- 
ing permanent  teeth  by  moving  the  deciduous  teeth;  (5)  in  determining 
more  exactly  than  can  be  done  with  the  single  radiograph  the  size  and 
location  of  a  pus  cavity  or  cyst;  (6)  in  cases  of  fracture  of  the  mandible; 
(7)  in  locating  exactly  bone  "whorls,"  calculi  in  the  glands  or  ducts  of 
glands  and  foreign  bodies  in  the  antrum;  (8)  in  learning  the  size,  shape 
and  location  of  the  antrum  as  an  aid  in  opening  into  it ;  and  (9)  in  cases 
of  tumor  to  locate  more  definitely  the  offending  body. 


STEREOSCOPIC  RADIOGRAPHY 


317 


Plastic  KadiograDby. 

There  is  no  one  thing  which  so  Hmits  the  usefulness  of  the  radio- 
graph as  its  lack  of  good  perspective.  Hence  our  interest  in  stereoscopic 
radiography.     Hence,  also,  our  interest  in  plastic  radiography. 

Plastic  radiography  is  a  method  of  making  radiographs  in  such  a 
way  that  the  parts  stand  out  in  has  relief.     A  better  name  than  plastic 


1 

s     _. 

Fig.   353.      Plastic   reproduction   of   Fig.    34'; 


Fig.    354.      Fig.    353    enlarged. 


radiography  would  have  been  trick  radiography.     I  describe  the  method 
simply  as  a  matter  of  interest.     It  is  of  no  practical  value  whatever. 

The  following  are  the  steps  in  making  a  plastic 
CcchniC  Of  radiograph.     The  negative  is  made  as  usual.     For 

Plastic  convenience  in  referring  to  it  we  shall  call  the  nega- 

RadiOflfapby.  tive  the  first  picture.    From  the  first  picture  another 

picture,  the  second  picture,  is  made  on  a  photographic 
plate,  the  technic  for  doing  this  being  the  same  as  for  making  con- 
tact lantern  slides.  The  first  and  second  pictures  are  now  placed  to- 
gether, non-sensitive  sides  in  apposition,  held  up  to  the  light  and  moved 
about  until  the  parts  of  the  two  pictures  overlie  one  another  exactly.  They 
are  now  held  immovable  while  an  assistant  sticks  them  together  with 


3i8  DENTAL    RADIOGRAPHY 

paper  binding  strips.  Next,  place  them  in  a  printing  frame  and  make  a 
photographic  print  on  paper  (see  Figs.  335.  352,  353  and  354).  While 
the  exposure  is  being  made  the  printing  frame  must  remain  immobile 
and  the  light  must  pass  through  pictures  number  one  and  number  two  and 
strike  the  photographic  paper  at  an  angle  of  about  ninety  degrees. 

Instead  of  allowing  the  light  to  pass  through  pictures  one  and 
two  and  strike  the  photographic  paper  at  an  angle,  the  same  result 
may  be  accomplished  by  allowing  the  light  to  pass  straight  through  pic- 
tures one  and  two,  if  at  the  time  they  are  stuck  together  the  two  pictures 
are  almost,  but  not  quite,  in  perfect  overlying  opposition. 

Instead  of  making  the  print  on  paper  from  pictures  one  and  two, 
another  picture,  number  three,  may  be  made  on  a  plate,  and  from  this 
third  picture  photographic  prints  made  (Fig.  336). 

Plastic  radiography  is  simply  a  scheme  of  shading  radiographs 
Nothing  more  can  possibly  be  seen  in  the  plastic  production  than  could 
have  been  seen  in  the  original  negative,  though,  perhaps,  something  may 
be  seen  more  easily.  To  the  man  unacquainted  with  the  reading  of  radio- 
graphs the  plastic  pictures  seem  much  clearer,  but  to  the  man  of  experi- 
ence it  is  not  so  clear,  for  there  is  an  unavoidable  loss  of  detail  in  the 
making  of  the  plastic  reproduction. 

Figs.  352,  353  and  354  are  plastic  stereoradio- 

PlastiC  graphs.     It  is  interesting  to  pause  and  consider  the 

Stcreoradioai'apbS*       number  of  steps  necessary  to  make  Fig.  354.     First. 

the  negatives  were  made ;   from  these  the  "second 

picture"  of  the  plastic  method,  then  the  prints  on  photographic  paper, 

from  which  enlargements  were  made,  and  then  the  halftone. 

In  concluding  let  me  say  that  the  properly  made,  intelligently 
read  single  radiographic  negative  is  of  the  utmost  importance  and  value 
in  the  practice  of  dentistry.  Let  us  not  forget  this,  and  let  us  not  decry 
the  radiograph  because  our  efforts  in  stereoscopic  and  plastic  work  fail  to 
make  it  absolutely  infallible. 

*  For  a  further  consideration  of  dental  stereoscopic  radiography  see  Appendix, 
Chapter  X. 


APPENDIX 


APPENDIX  TO   CHAPTER  I 


Electricity 

To  make  the  meaning  of  the  word  "  phase,"  used  as  an  electrical  term, 
clear,  would  require  the  use  of  unnecessary  space  in  this  volume. 

The  operator  need  not  bother  about  the  phase  of  his  supply  currrent. 
As  it  readies  him  it  is  single  phase  and  X-ray  machines  are  always  built 
for  the  single  phase  current. 


•;tq 


320 


APPENDIX 

APPENDIX  TO  CHAPTER  II 


X  Ray  machines 

Some  eight  or  ten  special  dental  X-ray  machines  have  been  placed 
on  the  market  within  the  past  three  years.     The  machines  represent,  in 


Figure  355A. — Special  dental  X-ray  machine.      Transformer  or  Interrupterless  type.      Size:   24 
inches  wide,   20  inches  deep,   59  inches  high. 

their  construction,  the  three  standard  types  of  X-ray  machines,  viz.,  the 
transformer,  or  interrupterless  coil,  the  induction  coil  and  the  high-fre- 
quency coil. 


X-RAY   MACHINES 


321 


Figure  355B. — Special  dental  X-ray  machine.     Transformer  or  Interrupterless  type.     Size:   17 
inches   wide,    23    inches    deep,    37    inclies    high. 


Figures  355,  A  and  B,  and  356  are  representative  of  the  dental  trans- 
former type. 

Figures  357  and  358  are  representative  of  the  dental  induction  coil 
type.     The  tube  on  top  of  Fig.  357  is  a  valve  tube. 


322 


APPENDIX 


Figure  359  is  a  dental  X-ray  machine  of  the  high-frequency  coil  type. 

With  some  types  of  the  high-frequency  X-ray  coil  (Fig.  360)  the 
operator  has  at  his  disposal  the  high-frequency  current  for  electro- 
therapeutic  work. 

The  value  of  the  high-frequency  current  as  a  therapeutic  agent  in  the 
practice  of  dentistry  has  not  been   satisfactorily  established.     I   would 


Figure  356. — Special  dental  X-ray  machine, 
electrotherapeutic — attachment  on  the  top. 
high. 


Transformer    type,    with    high-frequency — i.    e.. 
Size:  21  inches  wide,  20  inches  deep,  71  inches 


suggest,  however,  that  the  man  with  such  a  current  at  his  disposal  might 
experiment  with  it  using  it  with  the  idea  that  it  is  a  cellular  massage. 

Some  coils  are  so  constructed  that  the  coil  proper  may  be  placed  on 
a  shelf  on  the  wall,  up  out  of  the  way,  the  controls  of  the  coils  or  switch- 
board being  mounted  elsewhere  and  within  easy  reach.  With  an  X-ray 
machine  installed  in  this  way  "  overhead  wiring  "  is  usually  necessary 

The  principle  of  the  overhead  wiring  system  is  illustrated  in  Fig.  361. 
The  terminals  of  the  coil  are  attached  to  the  overhead  wires.     On  the 


X-RAY    MACHINES 


323 


Figure    357.— Special    dental    X-ray    machine.      Induction    coil    type.      Size:    15    inclies    wide,    23 

inches  deep,   30  inches  high. 

overhead  wires  are  the  trolley  reels  which  fasten  to  the  tube.     The  con- 
venience of  overhead  wiring  is  great. 

It  will  be  observed  that  on  Fig.  362  there  are  the  usual  terminals,  viz., 
the  positive  and  negative  secondary  terminals  and  the  "  dead  "  or  "  false  " 


324 


APPENDIX 


Figure    358. — Special    dental    X-ray    machine.    Induction    coil    type.       Size:    30    inches    wide,    17 

inches  deep,  44  inches  high. 


terminal  to  which  the  vacuum  reducing  lever  is  attached.  Back  of  these 
terminals  are  two  others.  It  is  interesting  to  know  what  these  two  extra 
terminals  are  for. 

They  are  connected  directly  to  the  terminals  of  the  secondary  winding 


X-RAY    MACHINES 


325 


Figure   359. — Special   dental    X-ray  machine.      High-frequency   coil   type.      Size:    24    inches    wide, 

10  inches  deep,   52   inches  high. 

of  the  transformer  before  rectification,  so  that  the  current  dehvered  at 
these  two  terminals  is  high  potential  alternating. 

In  addition  to  the  safety  valve  action,  they  have  two  other  functions. 
One  is  to  indicate  when  the  disc  switch  is  out  of  synchronism.  While 
the  current  "  slopping  "  across  these  two  terminals  occasionally,  would  not 
indicate  anything  wrong  with  the  switch,  if  the  current  slops  across  reg- 


326 


APPENDIX 


ularly  and  in  considerable  quantity,  it  is  a  certain  indication  that  the  disc 
has  gotten  out  of  synchronism. 

The  remaining,  function  is  to  deliver  unrectified  alternating  current 
to  a  high-frequency  attachment,  should  the  user  of  the  transformer  desire 
to  operate  a  high-frequency  apparatus  in  connection  with  the  transformer. 
(Fig.  356.) 


Figure    S(>0. — X-ray    and    electrotherapeutic    machine.       High-frequency    type, 
wide,   IS  inches   deep,   48   inches  high. 


Size:    24    inches 


Figure  363  illustrates  what  is  called  a  dental 
Dental  X-Kay  Unit.  X-ray  "  unit."  There  are  several  points  of  interest 
regarding  its  construction.  Let  me  describe  the  one 
illustrated. 

Electrically  it  is  an  induction  coil  with  an  electrolytic  interrupter. 
The  first  "  units  "  were  all  induction  coils.  (Recently  "  units  "  of  the 
Tesla  or  high-frequency  type  have  been  placed  on  the  market.)  Being 
small  it  is  easily  movable  and  so,  with  the  tube  fastened  to  the  adjustable 
upper  part,  it  acts  as  a  tube  stand. 

The  X-ray  tube  used  with  this  unit  is  a  special  one.  First,  a  valve 
tube  to  cut  out  inverse  is  built  into  it  as  is  indicated  by  the  illustration 
(Fig.  363)  which  shows  two,  instead  of  the  usual  one,  bulbular  part. 
Second,  for  protection  the  bulbular  part  of  the  X-ray  tube  proper  is  made 
of  lead  glass  save  for  a  window  of  ordinary  glass  through  which  the 
X-rays  are  directed  on  the  part  to  be  radiographed.  (When  in  operation 
the  tube  fluoresces  blue  except  just  at  the  window  of  ordinary  glass  which 


X-RAY    MACHINES 


327 


Figure   S61. — Overhead   wiring   system. 


328 


APPENDIX 


gives  the  usual  green  color.)  Third,  a  small  glass  compression  cylinder 
is  attached  as  part  of  the  tube.  Fourth,  the  regulating  chamber  and  the 
cathode  end  of  the  tube  are  connected  with  a  special  connection  the  func- 
tion of  which  connection   is   to   allow   "  just   enough  "   current   to   pass 


Figure  3G2. — 


through  it,  and  so  through  the  regulating  chamber,  to  keep  the  vacuum  of 
the  tube  constant,  i.  e.,  to  keep  it  from  raising. 

It  will  be  seen  from  the  foregoing  that  the  idea  of  the  "  unit  "  is 
simplification  for  the  operator  and  indeed  as  long  as  all  parts  are  in  good 
working  order  radiographs  may  be  made  with  it  by  simply  posing  the 
patient  and  switching  on  the  current  for  the  proper  length  of  time.  When 
it  becomes  necessary  to  make  some  adjustments,  however,  the  operator 
will  then  feel  the  need  of  the  information  set  forth  in  the  first  one  hundred 
pages  of  this  book. 


X-RAY   MACHINES 


329 


Figure  363. — Dental  X-ray  '"Unit."     Size:  IS  inches  wide,  IS  inches  deep,  46  inches  high. 


330  APPENDIX 

The  "  Hogan  silent  Roentgen  transformer "  is 
VB^..  iM^^us^A        said,  by  its  manufacturer,  to  be  a  transformer  or  in- 
terrupterless  type  of  X-ray  machme  which  is  so  con- 
structed that  it  rectifies  its  output  current  without  a  synchronous  rectify- 
ing disc  or  switch.     Other  manufacturers  tell  me  they  may  put  such  an 
X-ray  machine  on  the  market. 

the  X-Rav  Outfit  ^^  X-ray  outfit  consisting  of  a  transformer,  a 

Admitting  of  the      Coolidge  X-ray  tube  and  an  automatic  time  switch 

RcHabk  Control      ^*i"^its  of  the  most  perfect  and  reliable  control,  with 

the  least  effort  on  the  part  of  the  operator.     Such 

an  outfit  is  expensive. 


X-RAY  TUBES  AND  THE  X-RAYS 

APPENDIX  TO  CHAPTER  III 


331 


X'Rdv  Cubes  and  the  X-Rays 

Beginners  in  X-ray  work  seem  unable  to  reconcile  themselves  to 
accept  the  statement*  that  the  cathode  stream  passes  from  cathode  to 
target.  See  page  49.  So  let  me  emphasize  the  statement:  The  cathode 
stream  flows  in  the  opposite  direction  to  the  flow  of  the  electricity  through 
the  tube. 

Recently  it  has  been  satisfactorily  proved  that  the  X-rays  can  be 
reflected.  This  is  of  only  academic  interest,  however,  since  no  practical 
use  of  the  knowledge  has  so  far  been  made.  The  operator  back  of  a  lead 
screen,  using  a  mirror  to  observe  his  tube  and  patient,  must  not  think  from 
this  that  the  mirror  will  reflect  the  X-rays  to  him  as  it  reflects  the  image 
of  the  tube  and  patient. 


Figure  364. — Coolidge  X-ray  tube. 


eoolidge 
X-Kay  tube. 

other  X-ray  tubes. 


The  new  Coolidge  X-ray  tube  (Fig.  364)  built 
by  W.  D.  Coolidge  in  the  research  laboratory  of  the 
General  Electric  Company,  differs  radically  from  all 


Uacuum 
Control. 


It  differs  from  the  ordinary  X-ray  tube  described 
in  Chapter  V  so  much  that  it  is  difficult  to  compare 
the  two.  When  the  current  will  not  pass  through  an 
ordinary  X-ray  tube,  as  we  wish  it  to,  we  lower  the  vacuum  of  the  tube 
by  liberating  gases  in  it,  and  we  may  then  force  a  variable  amount  of 
milliamperage  through  it ;  depending  on  where  we  place  the  lever  of  the 


332  APPENDIX 

X-ray  machine  rheostat.  No  current  at  all  will  pass  through  the  Coolidge 
tube  until  the  tungsten  filament  or  coil  (Fig.  365)  is  heated,  and  then  not 
more  than  a  certain  amount  will  pass  through,  regardless  of  how  far  the 
lever  of  the  rheostat  of  the  X-ray  machine  is  advanced.  The  degree  of 
heat  of  the  tungsten  filament  controls  the  limit  of  the  milliamperage  which 
may  be  sent  through  the  tube. 

The  vacuum  of  the  Coolidge  tube  is  very  high  and  remains  practically 
the  same  always.  Temperature  of  the  tungsten  filament — i.  e.,  ionization 
— and  not  changes  in  degree  of  vacuum  due  to  gas  liberation,  governs 
the  amount  of  milliamperage  which  may  be  sent  through  a  Coolidge  tube. 


B. 


Figure    30.5. — Cathode    of    Coolidge    tube. 


When  a  Coolidge  tube  is  seen  in  operation  for  the 

TlUOrcscCttCC.  first  time  the  observer  is  surprised  to  find  that  it  does 

not  fluoresce.    The  heated  filament  is  seen  and,  if  the 

current  is  left  on  long  enough,  the  target  may  get  red  or  white  hot,  but 

the  green  fluorescence  of  the  ordinary  X-ray  tube  does  not  occur  at  all. 

If  the  polarity  of  the  machine  is  wrong,  it  will  be  shown  by  the  fact 

that  the  milliammeter  will  register  no  current,  regardless  of  how  high 

the  filament  temperature  may  be,  for  the  Coolidge  tube  allows  current  to 

pass  through  it  in  only  one  direction ;  from  filament  to  target. 

In  the  practice  of  radiodontia  one  need  have  little 
l)Catinfl.  fear  of  overheating  a  Coolidge  tube.     The  tube  will 

take  greater  quantities  of  current  over  a  longer  period 
of  time  than  the  radiodontist  will  find  it  necessary  to  use,  unless  the 
Coolidge  tube  is  one  of  the  finest  focus,  when,  to  keep  from  burning  the 
target,  not  more  than  about  25  milliamperes  should  be  sent  through  the 
tube. 


^  X-RAY  TUBES  AND  THE  X-RAYS  333 

.  The   Coolidge  tube   has   no   assistant  anode  or 

roolidae  Cube  regulating  chamber;  it  has  only  a  cathode  and  an 

anode  or  target.    Figure  365  is  an  illustration  of  the 
cathode. 

"  The  filament  (A)  Fig.  365,  which  forms  the  cathode,  consists  of 
a  flat  closely  wound  spiral  of  tungsten  wire.  By  means  of  a  rheostat  the 
heating  current  sent  through  the  filament  may  be  varied  from  3  to  5 
amperes. 

"  The  focusing  device  consists  of  a  cylindrical  tube  of  molybdenum 
(B),  Fig.  365,  mounted  concentric  with  the  tungsten  filament  and  with  its 
inner  end  projecting  about  0.5  mm.  beyond  the  plane  of  the  latter.  Be- 
sides acting  as  a  focusing  device  it  also  prevents  any  electron  discharge 
from  the  back  of  the  cathode. 


Figure   366. — Anode   of   Coolidge   tube. 


"  The  anti-cathode  or  target,  Fig.  366,  consists  of  a  single  piece  of 
wrought  tungsten  (C)  attached  to  a  molybdenum  rod  (D)  and  supported 
by  a  split  iron  tube  (E). 

"  The  cathode  filament  may  be  heated  by  means 
rathode  Tilament  *^^  ^  storage  battery  or  a  small  transformer.  The 
battery  is  universally  applicable.  The  transformer 
can  be  used  wherever  there  is  alternating  current  available,  either  from 
the  supply  mains  or  from  a  rotary  converter.  In  case  it  is  necessary  to  run 
from  the  same  source  of  supply  as  the  X-ray  transformer  the  filament 
current  transformer  is  not  to  be  recommended  for  radiographic  work 
where  there  is  much  line  drop.  In  many  cases,  however,  there  are  two 
•separate  sources  of  alternating  current  supply  and  then  the  filament  trans- 
former is  to  be  recommended  for  everything. 

"  In  Fig.  367  the  tube  is  shown  properly  con- 
Connectlons.  nected  to  tTie  storage  battery  and  the  X-ray  machine. 

It  must  always  be  borne  in  mind  that  the  entire  bat- 
tery circuit  is  brought  to  the  fiill  potential  of  the  tube  when  the  tube  is 
energized  for  use  and  that  the  wires  from  the  battery  should  therefore  be 


334 


APPENDIX 


as  thoroughly  insulated  from  the  patient  and  the  ground  as  the  tube  itself. 
"  The  full  circuit  is  shown  in  the  schematic  diagram,  Fig.  367,  in 
which  S  is  the  parallel  spark  gap,  M  the  milliammeter,  B  the  storage 
battery,  or  small  transformer,  R  the  rheostat  for  controlling  the  current 
in  the  filament  circuit,  and  A  an  ammeter  for  measuring  this  current.  The 
best  technic  for  the  Coolidge  tube  demands  the  use  of  an  ammeter  in 
the  filament  circuit.    The  meter  should  have  a  5-ampere  scale  large  enough 


Figure  367. — Diagram   of   Coolidge   tube   connections. 


to  be  easily  and  accurately  read.  The  meter  should  be  located  as  close  to 
the  operator  as  possible  and  in  such  a  way  that  it  can  be  easily  read  from 
the  operating  position. 

^   ^  .  .     ..  ,  "  The    technic    of    various    operators    and    the 

Cecbnic  for  Using  .       -^  ^.       r ,,    ,  ,  11. 

Goolidae  tube  sources  of  excitation  of  the  tube  vary  so  much  that  it 

is  difficult  to  make  detailed  suggestions  which  are 

universally  applicable.     The  following  general  considerations,  however, 

may  be  of  value : 

'Bear  these  two  things  in  mind:     First,  the  higher  the  filament 

current — i.   e.,  the  hotter  the  filament — ^the  greater  the  milliamperage 

which  can  be  sent  through  the  tube.    Second,  the  higher  the  voltage  backed 

up  by  the  tube — i.  e.,  the  longer  the  parallel  spark  backup — the  greater 

the  penetration  of  the  X-rays  produced.' 


X-RAY  TUBES  AND  THE  X-RAYS  335 

"  A  simple  method  of  starting  radiographic  work  with  the  Coolidge 
tube  is  as  follows  :" 

'  Take  a  case,  for  example,  where  the  operator  has  been  doing  his' 
work  with  the  rheostat  on  the  loth  button  with  his  tube  drawing  30 
milliamperes.  In  this  case,  all  that  is  necessary  with  the  Coolidge  tube  is 
to  set  the  main  rheostat  on  button  10,  light  up  the  filament  in  the  tube, 
having  the  filament  rheostat  handle  pushed  as  far  away  as  possible — i.  e., 
in — flash  the  main  switch  on  as  often  as  necessary  to  get  milliampere 
reading,  and  pull  on  the  handle  which  lets  amperage  into  the  filament 
and  heats  it,  until  the  tube  is  seen  to  be  drawing  30  milliamperes.  Having 
once  adjusted  the  tube  to  this  condition  the  operator  should  read  and 
record  the  amperage  in  the  filament  circuit.  To  reproduce  the  condition 
he  then  needs  merely  to  adjust  the  filament  current  to  this  same  amperage 
and  set  his  X-ray  machine  rheostat  on  the  same  button.  In  this  way,  after 
his  technic  is  once  established,  he  never  tests  his  tube  out  by  operating 
it,  but  is  guided  solely  by  the  ammeter  and  the  X-ray  machine  rheostat 
button.' 

"  In  other  cases,  the  radiographer  will  be  accustomed  to  adjust  his 
tube  by  means  of  milliammeter  and  the  parallel  spark  gap.  This  pro- 
cedure can  be  applied  equally  well  to  the  Coolidge  tube,  and  will  naturally 
be  the  one  first  used  in  all  cases  where  the  operator  is  not  familiar  with 
his  machine." 

Knowing  that  20  milliamperes  with  a  5-inch  parallel  spark  back-up  is 
desired,  start  by  setting  the  parallel  spark  gap  at  5  inches.  Light  the 
filament  of  the  Coolidge  tube  having  all  the  resistance  of  the  Coolidge 
control  rheostat  in — i.  e.,  the  handle  of  the  rheostat  pushed  in — and  so, 
the  least  possible  current  in  the  tube  filament.  Start  with  the  X-ray 
machine  rheostat  on  a  low  button.  Flash  the  main  switch  of  the  X-ray 
machine  whenever  readings  of  the  milliammeter  are  desired  and  manipu- 
late the  Coolidge  control  rheostat  and  the  X-ray  machine  rheostat 
alternately  until  20  milliamperes  are  passing  through  the  tube  and  a  spark 
will  jump  only  a  5-inch  parallel  spark  gap  and  no  more.  "  Widen  the 
parallel  spark  gap  now  and  everything  is  set  ready  for  the  radiographic 
exposure  to  be  made.  As  before  the  operator  reads  and  records  the 
amperage  in  the  filament  circuit  and  the  number  of  the  rheostat  button 
on  the  X-ray  machine  and  is  subsequently  guided  solely  by  these  records." 

Records  for  each  Coolidge  tube  must  be  made,  as  records  of  one  tube 
cannot  be  applied  to  another  and  the  same  radiographic  results  obtained. 

"  The  tube  may  be  safely  run  with  the  target  at  white  heat.  If 
excessively  high  energy  inputs  are  employed,  the  tungsten  at  the  focal 
spot  melts  and  volatilizes.    This  results  In  a  sudden  lowering  of  the  tube 


336  APPENDIX 

resistance  and  in  blackening  of  the  bulb.  The  instability  in  resistance 
disappears  instantly  upon  lowering  the  energy  input,  and  no  harm  has 
been  done  to  the  tube — that  is,  unless  it  is  to  be  used  for  the  production 
of  the  most  penetrating  rays  which  it  is  capable  of  emitting.  In  this  case, 
a  heavy  metal  deposit  on  the  bulb  is  undesirable,  as  it  interferes  with 
smooth  running  at  high  voltages. 

"  The  tube  should  not  be  run  with  voltages  higher  than  that  corre- 
sponding to  a  lo-inch  spark  gap  between  points  (that  is,  it  should  not  be 
made  to  back  up  more  than  a  lo-inch  parallel  spark). 

"  For  long  continued  running  in  an  enclosed  space  and  with  heavy 
energy  inputs,  it  will  be  necessary  to  provide  some  means  of  cooling  the 
glass,  as  by  a  small  fan  or  blower.  The  glass  can,  however,  safely  be 
allowed  to  get  very  hot.  It  is  all  right  so  long  as  it  does  not  soften  and 
draw  in. 

"  In  running  the  tube  on  an  induction  coil,  a  valve  tube  should  be 
used  in  case  heavy  energy  inputs  are  to  be  employed.  So  long,  however, 
as  the  temperature  of  the  focal  spot  is  not  made  to  approximate  that  of 
the  cathode,  the  tube  will  satisfactorily  rectify  its  own  current. 

"  The  tube  can  be  furnished  with  three  sizes  of  focal  spots :  broad, 
medium  and  fine.  For  therapeutic,  fluoroscopic  and  most  radiographic 
work  the  medium  focus  tube  will  be  found  suitable.  If  extremely  sharp 
definition  is  desired,  the  fine  focus  tube  should  be  used." 

The  Coolidge  tube  is  not  in  more  general  use  for  two  reasons :  ( i ) 
It  is  so  much  more  expensive  than  the  ordinary  gas  tube.  (2)  It  pro- 
duces a  great  number  of  vagrant  X-rays  (the  entire  stem  of  the  anode 
gives  off  X-rays)  which  sometimes  interfere  with  the  making  of  clear 
radiographs. 

The  two  common  injuries  from  sending  too 
^^^^^  r^"^**  "^"^^  current  through  an  X-ray  tube  are :  ( i ) 
Overheating  of  the  glass  and  consequent  puncture 
in  the  region  of  the  cathode.  (2)  Burning  of  the  target  at  the 
focal  spot.  To  overcome  the  danger  of  puncture  in  the  region  of  the 
cathode,  tubes  are  now  made  with  a  cathode  collar,  or  jacket,  of  steel. 
(See  Fig.  368.)  Tubes  of  this  design  are  capable  of  transmitting  much 
more  current  than  the  ordinary  tube  without  danger  of  puncturing  in  the 
cathode  region.  Tubes  with  cathode  collars,  which  the  writer  has  seen 
in  operation,  show  a  light  ring  in  the  inactive  hemisphere  giving  the  tube 
somewhat  the  appearance  of  a  tube  with  inverse  current  passing 
through  it. 

The  finer — i.  e.,  the  smaller — the  focal  point,  the  place  where  the 
cathode  stream  strikes  the  target,  the  more  likely  burning  of  the  target 


X-RAY  TUBES  AND  THE  X-RAYS 


337 


is  to  occur.  Thus  a  tube  with  a  very  fine  focal  spot  should  have  not  more 
than  about  20  to  40  milliamperes  sent  through  it,  while  the  same  sort  of 
a  tube  with  a  medium  or  broad  focal  spot  may  transmit  80  to  200  mil- 
liamperes without  injury  to  the  target. 

Tungsten  targets  are  capable  of  withstanding  much  more  heat  than 
platinum  targets. 

Figure  369  shows  a  ring  in  front  of  the  target.  The  functions  of 
the  ring  are:     (i)     To  sharpen  the  focal  spot.     (2)     To  overcome  the 


Figure    368. — X-ray  tube  with  protection   cathode  collar. 


initial  resistance  in  tubes  of  high  vacuum.     (3)    To  decrease  uneven  heat- 
ing at  the  cathode. 

Figure  370  is  a  type  of  valve  tube  differing  in 

mechanical  construction   from  Figs.  51   and  52.     A 
valve  tube  of  this  type  is  built  into  the  X-ray  tube 
illustrated  in  Fig.  83. 

Some  special  feature,  or  combination  tubes  are 
now  being  manufactured  to  operate  particularly  on 
"  Radiographic  Units."  These  tubes  may  have  built 
into  them  as  an  integral  part  any  one  or  all  of  the  following:  (i)  a 
valve  (2)  a  protection  bulh  of  lead  glass  (3)  a  cylinder,  through  which 


Cube. 


Combination 
tubes. 


338 


APPENDIX 


the  X-rays  are  directed  on  the  part  being  radiographed,  to  cut  out 
secondary  X-rays  (4)  a  filter,  consisting  of  a  sheet  of  aluminum  in  the 
bore  of  the  cylinder  (5)  a  special  vacuum-regulating  device  consisting  of 
a  connection  between  the  regulating  chamber  and  the  cathode  end  of 


Figure  309. 


1 


Figure  370. — Valve   tube. 


the  tube,  which  connection  is  of  the  proper  electrical  resistance  to  carry 
the  right  amount  of  electricity  to  keep  the  vacuum  of  the  tube  the  same. 
In  principle,  the  connection  between  the  tube-regulating  chamber  and 
the  cathode  end  of  the  tube  is  a  tube-regulating  spark  gap  which  is  set  at 
a  definite  distance.     As  I  have  mentioned  elsewhere   (Chapter  V)   the 


X-RAY  TUBES  AND  THE  X-RAYS 


339 


tube-regulating  spark  gap  may  be  set  at  a  certain  distance  and  left  there 
while  the  tube  is  in  operation.  Since  the  resistance  of  the  tube-regulating 
spark  gap,  which  is  to  be  set  while  the  tube  is  in  operation,  should  be  less 
as  the  tube  gets  older,  it  is  not  quite  right  for  manufacturers  to  claim  that 
the  special  connection  now  under  consideration  makes  the  control  of  the 
tube  "  absolutely  automatic."  When  the  tube  is  new  its  vacuum  control 
may  be  automatic,  but  as  it  gets  old  manipulation  (i.  e.,  lessening  of  re- 


Figure  371. — Hydrogen  X-ray  tube. 


sistance)  of  the  special  connection,  between  the  regulating  chamber  and 
the  cathode  end  of  the  tube,  becomes  necessary.  The  greatest,  or  as  I 
see  the  thing,  the  only  advantage  of  the  "  special  automatic  (?)  vacuum 
control  connection  "  is  that  it  admits  of  reduction  of  the  vacuum  of  a 
tube  without  any  sparks  occurring,  as  they  do  at  an  atmospheric  tube- 
regulating  spark  gap.  This  is  a  definite  advantage  when  the  tube-regulat- 
ing spark  gap  is  at  the  tube,  for  then  there  is  no  disagreeable  sparking  in 
the  vicinity  of  the  patient,  but  is  not  an  advantage  if  the  tube-regulating 
spark  gap  is  on  the  X-ray  machine.     (See  page  49.) 


340  APPENDIX 

Figure  371  illustrates  a  type  of  tube  known  as 
riih*<  the  "  hydrogen  tube  "  because  the  gas  used  to  lower 

the  vacuum  is  hydrogen.  Some  hydrogen  tubes  admit 
of  regulation  in  either  direction ;  that  is,  their  vacuum  may  be  either 
raised  or  lowered  while  others  admit  only  a  regulation  of  lowering. 
Figure  371  shows  the  special  device  by  means  of  which  the  vacuum  is 
regulated  instead  of  the  usual  tube-regulating  spark  gap. 

The  writer's  experience  with  X-ray  tubes  has 

7711% A#  T|^*iiiiiii  ^  -^ 

ruh*  to  Kuu  taught  him,  when  purchasing  a  new  tube,  never  to 

buy  one  which  backs  up  more  than  five  inches  parallel 
spark.  One  which  backs  up  only  three  inches  parallel  spark,  with  use,  will 
soon  be  backing  up  more.  But  a  tube  which  backs  up  more  than  five 
inches  parallel  spark  when  new  will  soon  be  backing  up  so  much  parallel 
spark — i.  e.,  will  soon  have  such  a  high  vacuum — that  the  best  dental 
radiographic  results  cannot  be  obtained  with  it. 


APPENDIX  TO  CHAPTER  V 


makiitd  Dental  Kadiograpbs. 

new  Pose  for  Trontal,     ^^^    advantage    of    having    a    well    sectioned    skull, 
ethmoidal,  and  max-    to  the  operator  who  wishes  to  do  sinus  work,  can- 
lllary  Sinuses.  j^q^-  jjg  overestimated.    Before  one  becomes  proficient 

in  this  work,  experimentation  on  a  skull  is  necessary. 

A  comparatively  new  and  most  excellent  pose  for  making  antero- 
posterior radiographs  of  the  frontal  sinuses,  ethmoid  cells,  and  antra  is 
illustrated  in  Fig.  t,'/2.     Fig.  t,/2i  is  a  diagrammatic  drawing  explanatory 


of  Fi( 


372. 


Fig.    372,      Pose    for    frontal    sinuses,    antra    and    eth- 

moids.      (Published  by  courtesy  of  Interstate 

Medical  Journal.) 


SPHENOID 
SINUS 

ETHMOID 
CELLS 
FRONTAL 
SINUS 

ANTRUM 


Fig.    373.       Diagrammatic    drawing    ex- 
planatory of  Fig.  372.     (Interstate 
Medical  Journal.) 


Figure  374  is  a  radiograph  made  from  the  pose  illustrated  in  Fig. 
372,  and  Fig.  375  is  a  diagrammatic  drawing  explanatory  of  Fig.  374. 


Spbenoid  Sinus. 


mastoids. 


Figures    376,     377    and    378    illustrate    poses     for 
sphenoid  exposures. 

Figure    379    illustrates    a    pose    for    mastoid    ex- 
posures. 

341 


342 


APPENDIX 


Fig.  374.      Radiograph  made  from  pose.  Fig.  372.      {Interstate  Medical  Journal.) 


f-^ 


Fig.    375.      Diagrammatic    drawing   explanatory    of    radiograph,    Fig.    374.       (Interstate    Medical 

Journal.) 


MAKING    DENTAL    RADIOGRAPHS 


343 


344 


APPENDIX 

This    device     (Fig.   380)     facilitates    the    interpre- 
tation  of  radiographs  of  the  head.     Correct  inter- 
pretation is  sometimes  more  difficult  on  account  of 
the  light  area  around  the  radiographic  image  on  the  negative.     The  In- 


Troittal  Sinus 
Tntensificr. 


Fig.    379.       Pose    for    mastoids.       (Interstate    Medical    Journal.) 


tensifier  is  simplicity  itself.  It  consists  of  heavy  lead  plate  which  fits 
into  a  surrounding  heavy  iron  frame ;  both  are  covered  w^ith  felt.  Place 
the  intensifier  on  the  plate.  The  lead  plate  is  now  removed  and  the 
patient's  head  is  placed  in  the  frame.  The  exposure  is  made  and  the  lead 
plate  replaced.  The  iron  frame  is  then  removed  carefully,  leaving  the  lead 
plate  covering  the  part  which  has  been  exposed.  Two  flashes  of  the  X- 
rays,  after  the  removal  of  the  frame,  exposes  the  photographic  plate 
where  the  frame  has  rested  and  makes  the  negative  black,  except  just 
that  part  of  it  on  which  the  radiograph  appears. 


MAKING    DENTAL    RADIOGRAPHS 


345 


Figure  381   illustrates  a  "  kassett  "   or  plate  holder 
K^SSCtt.  which  may  be  used  instead  of  envelopes  to  protect 

plates  from  light  while  handling  them  to  make  radio- 
graphs.   Kassetts  are  especially  useful  when  intensifying  screens  are  used. 


Fia.   IjSO.      P^Kintiil    siiui^    intLiibifier. 


-— I 


tbc  Benoist 
Penetrometer. 


Fig.   381.     Kassett. 

The  exact  penetration  of  the  X-rays  can  be  de- 
termined accurately  and  easily  by  the  use  of  the 
Benoist  penetrometer.  (Fig.  382.) 
Lay  the  penetrometer  on  the  plate  where  it  will  be  exposed  while 
the  exposure  for  the  radiograph  is  being  made.  When  the  plate  is  de- 
veloped the  radiograph  of  the  penetrometer  will  appear  as  a  circle  of 
varying  shades  surrounding  a  circle  or  spot.  The  shade,  counting  from 
the  darkest  as  number  one,  which  matches  the  center  or  spot  is  the  pene- 
tration of  the  tube  on  the  Benoist  scale. 

"  Very  low  vacuum  tubes  showing  a  penetration  of  only  about  tWQ 


346 


APPENDIX 


will  not  give  good  radiographs  of  any  part  thicker  than  the  hand,  regard- 
less of  the  length  of  exposure.  Before  such  a  tube  is  used  its  vacuum 
should  be  coaxed  up  by  running  a  current  of  two  or  three  milliamperes 
through  it  for  a  few  minutes  each  day." 


Fig.    384A.      Ketchan    film-holder    in    posi- 
Fig.   383.      Small  lead  protection  box  for  films.  tion  for  lower  third  molar. 

Repeated  and  prolonged  efforts  to  make  radiographs  with  a  tube, 
the  vacuum  of  which  is  too  low  may  result  in  producing  an  X-ray  burn. 
When  a  tube  gives  8  or  lo  Benoist  penetration  it  will  probably  not 
make  good  radiographs.  They  will  be  lacking  in  contrast  because  the 
X-rays  are  so  penetrating  that  they  penetrate  bone  and  soft  parts  alike. 
Negatives  made  with  a  tube  of  such  high  penetration  sometimes,  besides 
lacking  contrast  and  detail,  will  show  a  brown  color  from  the  glass  side 
of  the  negative.  This  brown  color  is  indicative  of  what  is  called  "  burn- 
ing up  the  emulsion  "  with  a  "  too-high  "  penetration. 

Figure    383    ilustrates    a    small    lead    box ;    inside 
Small  Ewd  Box.        dimensions  about  5x6  inches,  which  is  a  most  prac- 
tical one  for  small  dental  films. 


MAKING   DENTAL   RADIOGRAPHS 


347 


Hctcbam  Tilm 


Figure  384  illustrates  the  Ketcham  film  holders, 
the  most  elaborate  set  devised.  Figure  384A  is  a 
radiograph  showing  a  Ketcham  film  holder  in  posi- 


tion for  a  lower  third  molar. 


Fig.  3t>6.      Dental  radiograph  made 
directly  on  bromide  paper. 


Fig.   385.      Radiograph    made   on  bromide   paper. 


Fig.  387.  The  negative  for  this 
radiograph  was  made  at  the  same 
time  with  Fig.  386,  the  film  and 
the  bromide  paper  being  enclosed 
in  the  same  packet. 


Hadi09rap1)$  made 
on  Paper. 


Instead  of  using  a  photographic  plate  or  film,  a 
radiograph  may  be  made  directly  on  photographic 
paper.  This  paper  should  be  the  most  sensitive  made, 
so  that  the  exposure  will  be  as  short  as  possible.  Glossy  "  bromide  "  paper 
is  the  best.  Figure  385  illustrates  a  radiograph  of  the  hand  made  di- 
rectly on  bromide  paper.     (Reduced  one-half.) 


Direction  Of  X-ravs       Figures    388    and    389    show    very   clearly    that    di- 

tbrougb  the  tectl)       rectmg  the  X-rays  through  the  posterior  teeth  at  right 

Tigs.  3$$  and  3$9.      angles  to  the  long  axis  of  the  tongue  does  not  mean 

at  all  that  the  rays  pass  straight  through  the  tooth  from  buccal  to  lingual 


348 


APPENDIX 


Lines  A  at  right  angles  to  long  axis  of  tongue;  lines  B  straight  through 
the  teeth  from  buccal  to  lingual. 


Fig.    389. 

If  it  is  at  all  possible,  it  is  certainly  most  desir- 
able to  have  the  dark  room  well  ventilated.  The 
writer  uses  a  "  Sirocco  "  suction  fan  to  force  air  into 
the  dark  room  and  a  ventilator  diagramed  in  Fig.  390  to  provide  a 
means  of  egress.     No  light  is  let  in  by  this  arrangement.     In  very  hot 


Uentilation  of 
Dark  Room. 


MAKING  DENTAL  RADIOGRAPHS 


349 


weather,  open  the  ice  box  or  refrigerator  (if  the  dark  room  is  equipped 
with  one)  and  direct  the  breeze  of  an  electric  fan  onto  the  ice.  This  will 
lower  the  temperature  of  the  room  quite  noticeably. 

Figure  391  illustrates  how  an  extra-oral  radio- 
graph may  be  made  on  a  comparatively  small  film. 
By  means  of  the  Van  Woert  film  holder  and  in- 
dicator, the  X-rays  may  be  directed  at  right  angles 
to  the  surface  of  the  film.  When  radiographing  the 
upper  teeth,  it  is  not  the  exactly  correct  pose  to  have  the  X-rays  strike  the 
film  surface  at  right  angles ;  it  is  almost  correct,  however. 


Small  €xtra-Oral 
Radiograph  on  Tilm. 

Uan  moert  Tilm 

1)0l(lcr  and  Indicator 

Tig.  T. 


.   391.      Pose   for  extra-oral   radiograph 
made   on   film,    and    the   radiograph. 

Beginners  will  probably  find  the  indicator  a  help.  Men  experienced 
in  the  practice  of  radiodontia  will  not  be  likely  to  use  it  except  as  a  means 
of  making  a  series  of  exposures  of  the  same  part  when  they  particularly 
desire  to  make  each  exposure  with  the  rays  passing  through  the  parts  and 
striking  the  film  at  the  same  angle  every  time.  As  a  means  of  duplicating 
a  pose  exactly,  an  indicator  of  some  sort  is  a  necessity. 

The  soft  tube  technic  for  dental  radiographic 
rffhMlf  work    is    becoming    definitely    more    popular.      The 

parallel  spark  gap  is  set  for  only  about  4  inches  and 
the  tube  so  reduced  in  vacuum,  if  necessary,  that  even  this  short  gap  is 
not  "  backed  up."  Splendid  black  and  white  negatives  are  made  by  this 
technic.  It  is  important  to  know  that  the  time  of  exposure  necessary, 
and  so  the  milliampere-second  dose,  is  greater  when  the  soft  tube  technic 
is  employed. 

Both    Drs.    Ottolengui    and    Barber,    each    indepen- 

Rubff  Dam^cffl)       ^^"^  °^  *^^^  other,  have  suggested  to  the  writer  that 
a  rubber  dam  clamp  may  be  used  to  hold  the  film 
packet  in  position  during  the  exposure. 


350 


APPENDIX 


Ucrtical  Position  of  The  man  who  makes  only  a  few  film,  dental 

films  in  Developer       radiographs   will   find   it   convenient  to  use   a  glass 
rlXCr.  tumbler  or  cup  instead  of  trays  for  his  developing 

and  fixing  solutions  and  wash  water.  Fasten  the  exposed  films  to  a  hook 
clip.  (Fig.  119.)  Hook  the  clips  over  the  side  of  the  tumbler  or  cup 
suspending  the  film  inside.  This  makes  the  handling  of  the  films  very 
easy  and  affords  the  advantage  of  having  the  films  in  the  developing  and 


Fig.   F.      Van   Woert   film-holder   and   indicator. 


fixing  solutions  in  a  vertical  position  so  no  sediment  can  settle  on  the 

sensitive  surface. 

,,       ,,     „,    .-  A  vessel,  something  like  a  berry  dish,  will  be 

UCSSCl  for  UlasDing       ^^^^^   ^^^^^^   ^^^^    ^   ^^^^    foj.   cashing   small    film 

tllm  negatives  negatives,  for  the  water  falling  from  a  faucet  causes 

more  movement  of  the  water  in  such  a  dish  and  so  washes  the  negatives 

better  and  quicker.     Negatives  can  be  picked  up  in  such  a  dish  with 

greater  ease  than  they  can  from  a  tray.     Such  a  dish  should  not  be  used 

when  the  tap  water  is  warm,  as  the  movement  of  the  negatives  will  scar 

them. 

In   cases   where   there   is   an   excessive   flow   of 

$alit)ation.  saliva,  particularly  when  the  outfit  used  necessitates 

a  rather  long  exposure,  if  the  films  are  protected 

from    moisture    only    by    paper,    it    is    expedient    to    take    the    film 

packet    from    the    mouth    after    exposure    and    immediately    squeeze    it 

between  pieces  of  blotting  paper.    This  may  avoid  wetting  the  films  inside 

the  packet. 


MAKING  DENTAL  RADIOGRAPHS  351 

Old  n^D^lou^r  With  use  both  the  developing  solution  and  the 

and  fixer  fixing  solution  will  wear  out  and   cease  to  act  on 

plates    or    films.     Wornout    developer    produces    a 

weak,    poor    negative.      Wornout    fixer    will    not    dissolve    out    all    the 

unacted-upon  silver. 

Development  Ulben  When    an    intensifying    screen    has    been    used 

Tntensifying  Screen       "highlights"  appear  immediately  when  the  plate  or 

is  Used.  film  is  placed  in  the  developer.     The  rule  to  develop 

20  times  as  long  as  it  takes  for  the  highlights  to  appear  does  not  apply 

when  an  intensifying  screen  has  been  used. 

Ceaving  Dark  Rocitl  ^^'  while  the  film  or  plate  is  in  the  developer,  it 

During  Development       becomes    necessary    to    leave    the    dark    room,    the 
Of  negtltive.  tray   containing   the   developer   and   the   developing 

plate  or  film  may  be  covered  with  a  heavy  board  on  the  down  side  of 
which  is  tacked  or  glued  thick  felt  or  plush.  This  will  protect  the  film 
or  plate  from  exposure  to  light  when  the  dark  room  is  opened.  If  a 
light-proof  drawer  is  available,  it  is  better  than  the  board;  the  tray  may 
be  placed  in  the  drawer  when  the  dark  room  door  may  be  opened  with 
safety. 

Instead  of  washing  the  negative  in  running  water 
**l)ypo-€liminator."  for  30  minutes,  after  fixing,  negatives  may  be 
soaked  in  "hypo-eliminators"  for  about  5  minutes, 
then  rinsed  in  water,  and  dried.  "Hypo-eliminators"  may  be  purchased 
at  photographic  supply  houses ;  directions  for  their  use  accompany  them. 
The  advantage  in  using  them  lies  chiefly  in  the  saving  of  time.  They  may 
also  be  used  in  the  summer  to  advantage,  when  tap  water  is  so  warm 
that  it  softens  the  emulsion  and  washing  is  fraught  with  the  liability  of 
spoiling  the  negative. 

When,in  the  course  of  a  day,  a  number  of  radio- 
forldentifSion^  graphs  are  made  of  different  patients,  unless  each 
negative  bears  some  distinguishing  mark,  one 
patient's  negatives  may  be  mistaken  for  another's.  To  avoid  this  con- 
fusion, number  the  patients  as  they  are  received,  then  number  the  nega- 
tives so :  As  soon  as  the  films  are  unwrapped  in  the  dark  room,  place  the 
patient's  number  in  a  corner  of  the  film,  marking  it  on  the  sensitive  side 
with  a  lead  pencil.  The  lead  pencil  mark  can  be  seen  on  the  finished 
negative. 

Lately  I  have  seen  an  elaborate  system  of  marking  each  negative, 
where  several  are  made  of  the  same  mouth,  to  enable  the  operator,  from 
the  markings,  to  determine  what  part  of  the  mouth  each  negative  repre- 
sents. If  the  sensitive  side  of  the  film  presents  toward  the  teeth  at  the 
time  of  exposure,  as  it  should  always,  the  operator  should  be  able  to 
determine,  from  the  appearance  of  the  radiograph,  what  part  of  the 
mouth  it  represents.  And  if  an  operator  cannot  do  this,  he  does  not  know 
enough  about  radiodontia  to  interpret  dental  radiographs  at  all. 


352 


APPENDIX 


As  the  name  implies,  fogged  negatives  have  a 
Tossed  Plates.  foggy   appearance.      Fogging   may   be  produced   in 

many  different  ways.  For  example  (i)  By  the 
X-ray  light,  if  the  lead  of  the  protection  box  is  not  thick  enough  or 
if  it  is  placed  too  close  to  an  active  X-ray  tube.  (2)  By  a  dark 
room  lantern  which  gives  too  much  light.  (3)  By  getting  the  plate 
too  near  the  dark  room  lantern.  (4)  By  exposure  to  X-rays  in  some 
office  other  than  your  own ;  the  postman  might  carry  your  films  or 
plates  into  another  office  before  delivering  them  to  you.  (5)  By  using 
the  developing  solution  too  warm.  A  fogged  plate  is  sometimes  referred 
to  as  a  "light-struck"  one.  When  the  action  of  the  fixing  solution  is 
well  under  way,  but  not  complete,  the  negative  appears  to  be  fogged. 

J.    .  _  "In  extremely  hot  or  damp  weather  or  in  hot 

Summcirtinie  tip.        dark   rooms,   plates   will   dry   quicker,   and   stand   a 

very  warm  wash  water  if  you  will  put  them  into  a 

tray  containing  a  solution  of  i  oz.  of  chrome  alum  to  10  ozs.  water  for  a 

couple  of  minutes  after  removing  them  from  the  developer  solution. 

"The  developer  temperature,  remember,  should  always  be  between 
65°  and  68°  Fahr.  to  give  the  finest  results." 

If  you  do  not  have  a  thermometer  to  determine  the  temperature  of 
the  developer,  get  one. 

An  ice  box  in  the  dark  room  in  the  summer  is  worth  more  than  it 
costs. 

Along  with  much  other  valuable  information 
ni  J^^^^  iP  Geo.  W.  Brady  gives  the  following  in  his  excellent 

Plate  nesatlm.         p^^phiet  "Paragon  X-ray  Pomters :" 

"  Ninety-nine  per  cent,  of  plate  defects  are  due  to  careless  manipula- 
tion in  the  dark  room. 

"Pitted  negatives  are  due  to  too  slow  drying.  The  gelatine  swells 
and  gelatine  eating  microbes  settle  on  the  plate,  leaving  transparent  spots 
of  blotches. 

"Stains  are  generally  due  to  improper  fixing.  The  hypo  may  be 
decomposed  or  the  bath  may  not  contain  sufficient  acid.  If  the  plates  are 
not  rinsed  thoroughly,  sufficient  alkali  would  soon  be  carried  over  from 
the  developer  to  neutralize  the  acid  in  the  hypo  bath.  This  may  cause 
green  or  blue  stains,  even  though  the  plate  is  fixed  in  absolute  darkness. 
Stains  may  be  due  to  insufficient  washing.  Greenish  stains,  pink  by 
transmitted  light,  are  usually  due  to  too  warm  developer,  or  too  long 
development  of  under  exposed  plates.  Examination  of  the  plates  by  a 
bright  light  before  fixation  is  complete  should  be  avoided. 

"Pin  holes  are  always  a  defect  in  the  handling  of  the  plate.  They 
are  never  the  result  of  defect  in  manufacture.  They  may  occur  in  either 
tank  or  tray  development.  The  remedy  is  to  go  over  the  surface  of  the 
plate  with  cotton  or  to  rock  the  plate  vigorously  when  first  put  into  the 
developer. 

"Semi-transparent  spots  on  plates  developed  in  tanks  are  generally 
due  to  air  in  the  water  due  to  high  water  pressure,  or  to  the  cold  and 


MAKING   DENTAL  RADIOGRAPHS  353 

hot  water  pipes  running  closely  together.  The  remedy  is  to  stir  the  water 
thoroughly  and  then  allow  it  to  stand  long  enough  for  the  air  to  escape. 

"Irregular  transparent  spots  may  be  due  to  oil  getting  on  the  film, 
or  to  a  scum  which  sometimes  occurs  on  the  surface  of  the  developer 
when  left  standing  for  some  time. 

"Black  spots,  sometimes  with  a  tail,  are  due  to  iron  getting  into  the 
solution,  possibly  from  the  water  pipes. 

"Small  dark  spots  with  sharp  edges  are  generally  caused  by  water 
spattering  on  the  plates  before  development. 

"Streaky  plates  may  be  caused  by  an  old  hypo  solution  in  a  ribbed 
fixing  box.  They  may  also  be  due  to  always  rocking  the  tray  in  one 
direction. 

"Defective  plates  are  so  rare  that  the  trouble  can  generally  be 
located  in  the  X-ray  laboratory.  If  any  question  should  arise,  send  the 
manufacturer  of  the  plates  the  numbers  on  the  bottom  of  the  box, 
together  with  a  few  of  the  unexposed  plates,  or  allow  some  fellow  radiog- 
rapher to  expose  and  develop  some  of  your  plates  without  telling  him 
what  your  troubles  are." 

A  small  film  dental  negative  which  is  finely  checkered  with  little 
dark  lines  is  one  which  has  been  spoiled  by  warm  solutions  or  warm  wash 
water. 

Danger  of  ToSding  "It  is  not  good  policy  to  have  the  ruby  light 

Tfom  Dark  Room        shining  into  the  tray  throughout  the  entire  course  of 

Cantcrn.  development ;   in   fact,   it  is   advisable   that   the   red 

light  be  only  allowed  to  shine  on  the  plate  when  the  developer  is  poured 

on  to  see  that  it  is  properly  covered  and  then  the  tray  kept  shaded  from 

direct  light  till  development  is  nearly  completed. 

"Remember  that  very  few  lights  are  safe.  To  test  yours,  take  a 
small  plate,  lay  a  bunch  of  keys  on  it  directly  under  the  light  at  a 
distance  of  about  a  foot  for  a  couple  of  minutes,  then  develop  the  plate 
in  darkness  with  your  regular  developer  for  four  or  five  minutes.  If 
your  light  is  an  unsafe  one,  the  bunch  of  keys  will  show  distinctly  on  the 
plate."* 

Photographic  prints  made  on  paper  from  nega- 
Ifiaking  rrilttS  tives  may  be  made  more  glossy  and  altogether  more 

^*  beautiful  by  placing  them  on  a  ferrotype,  or  squeegee 

board.  The  ferrotype  is  a  sheet  of  metal  on  one  side  of  which  is  baked 
black  enamel.  After  the  prints  are  washed  they  are  laid  face  down  on 
the  enamel  side  of  the  ferrotype,  and  rolled  with  a  rubber  covered  roller 
made  for  this  purpose.  The  ferrotype  is  now  set  on  end,  and  as  the 
prints  dry  they  fall  off  or  can  be  picked  ofif.  Before  placing  the  prints  on 
the  ferrotype  the  enamel  surface  should  be  polished  with  ferrotype  polish. 
Ferrotype  polish  is  a  solution  of  paraffin  in  benzine.  It  is  put  on  the 
ferrotype,  allowed  to  dry  for  a  few  minutes,  then  the  enamel  surface 
polished  with  chamois  skin.  If  the  prints  do  not  come  off  the  ferrotype 
as  they  should,  but  stick  tightly,  more  paraffin  may  be  added  to  the 
polishing  solution.     Several  things  may  cause  prints  to  stick  to  the  ferro- 

*  "  Paragon  X-ray  Pointers,"  by  Geo.  W.  Brady. 


354 


APPENDIX 


type.  If  left  in  the  wash  water  too  long  or  if  too  much  pressure  is 
brought  to  bear  on  them  with  the  roller  they  will  stick.  Washing  the 
ferrotype  with  soap  and  water  will  assist  in  preventing  sticking  of  the 
prints.  Occasionally  a  ferrotype  will  be  found  on  which  the  prints  always 
stick  and  it  must  be  discarded  and  another  ferrotype  obtained. 

Lantern  slides  may  easily  be  made  from  a  good 
Eantern  Slides.  negative.     A  lantern   slide  plate   is   a   photographic 

plate  3K^4  inches,  manufactured  especially  for  the 
purpose.  Like  all  other  photographic  plates,  it  should  be  "  worked  "  in  the 
ruby,  never  the  orange,  light.  The  negative  is  placed  in  the  printing 
frame,  sensitive  side  up,  and  the  slide  laid  over  it,  sensitive  side  down. 
(We  are  making  what  is  called  a  "contact"  lantern  sHde;  the  lantern 
slide  plate  is  in  contact  with  the  negative.)  The  average  celluloid,  dental, 
radiographic  negative  is  of  such  density  that  the  time  of  exposure  of  the 
plate  to  a  i6-C.  P.  electric  light,  at  a  distance  of  two  feet,  is  about  i 
second.  Allow  the  slides  to  remain  in  the  developer  a  few  seconds  after 
the  radiograph  shows  best,  until  it  shows  a  little  too  dark.  Rinse  in  water 
quickly  and  transfer  to  the  fixing  bath,  where  it  should  remain  until  the 
picture  shows  clearly  as  desired.  The  writer  uses  Imperial  lantern  slide 
plates  and  Seed's  prepared  metol-hydrochinone  developer.  After  fixing, 
the  slide  is  washed  and  dried  the  same  as  any  photographic  plate.  When 
dry  a  piece  of  transparent  glass,  the  same  size  as  the  slide,  is  laid  on  the 
film  side  of  the  slide  and  the  two  stuck  together  at  their  edges  with  binding 
tape,  such  as  is  used  for  passe-partout  work.  The  piece  of  clear  glass  is 
used  to  protect  the  emulsion  of  the  slide  against  scratching. 

When  a  lantern  slide  of  a  negative  larger  than  the  lantern  slide  plate 
is  desired,  a  contact  lantern  slide  cannot  be  made?  An  apparatus  similar 
to  the  one  illustrated  in  the  Appendix  to  Chapter  X  for  enlargement,  must 
be  used.  Light  is  directed  through  the  negative,  then  through  a  reducing 
lens  onto  the  lantern  slide.  When  the  lantern  slide  desired  is  from  an 
extra-oral  dental  radiograph,  even  though  the  plate  used  is  as  large  as 
8xio,  the  size  of  the  lantern  slide  will  usually  cover  the  part  of  the 
negative  of  interest  and  so  the  lantern  slide  plate  may  be  placed  over  the 
area  of  interest  and  a  contact  lantern  slide  made  of  that  part  of  the 
negative. 

Dr.  Kells  makes  lantern  shdes  of,  instead  of  from,  his  celluloid  dental 
negatives.    This  is  accomplished  as  follows  : 

On  a  clear  glass  3^x4  inches  place  a  piece  of  black  paper  the  same 
size,  with  a  hole  in  the  center  large  enough  to  show  all  of  the  negative  that 
the  operator  wishes  to  exhibit.  Place  the  negative  directly  over  this  hole 
in  the  paper.  Place  another  piece  of  glass  2>%^4  inches  over  the  whole 
and  bind  the  two  pieces  of  glass  together  at  their  edges  with  binding 
strips.  The  advantage  of  this  method  over  making  photographic  slides 
is :  The  ease  and  dispatch  with  which  they  may  be  made — a  dark  room 
and  equipment  is  not  necessary — and,  since  we  are  using  the  negative 
itself,  there  is  no  loss  of  detail  such  as  might  occur  when  the  other 
method  is  employed  and  a  new  picture  is  made  on  the  photographic  slide. 
The  disadvantage  is  that  the  negatives  with  good  detail  are  often  so  dark 
that  the  light  from  the  lantern  is  not  strong  enough  to  penetrate  them. 


MAKING   DENTAL  RADIOGRAPHS 


355 


Negatives  made  with  the  transformer  (interrupterless)  X-ray  machines 
are  best  for  lantern  sHdes  because  they  are  usually  not  so  dense  as  those 
made  with  the  other  types  of  X-ray  machines. 

Within  a  limit,  the  time  of  exposure  necessary 
Sbl(ffor^€xDOSurc  ^^^^^^  inversely  according  to  the  milliamperes  sent 
through  the  tube.  Thus  the  more  milliamperage 
sent  through  a  tube  the  shorter  the  time  of  exposure  necessary,  or  con- 
versely the  longer  the  exposure  given  the  less  milliamperage  need  be 
sent  through  the  tube.  The  action  on  the  photographic  emulsion  on  the 
plate  or  film  would  be  about  the  same  from  a  2-second  exposure  with  30 
milliamperes  passing  through  the  tube  as  from  a  3-second  exposure  with 
20  milliamperes  passing  through  the  tube.  So  we  have  come  to  measure 
exposures  in  milliampere-seconds.     (M.  A.  S.) 

Obtain  the  milliampere  seconds  by  multiplying  the  number  of  mil- 
liamperes passing  through  the  tube  by  the  number  of  seconds  the  current 
is  turned  on. 

If  the  distance  between  target  and  film  or  plate  varies  apply  the  rule 
that  the  time  of  exposure  necessary  varies  directly  with  the  square  of  the 
distance.     (See  Page  124). 

The  following  is  a  dental  M.  A.  S-  table  for  exposure: 


DISTANCE 

TIME  OF 

TIME  OF 

KIND  OF 

CONDITION 

FROM 

FILM  OR 

EXPOSURE 

EXPOSURE 

RADIO- 

OF TUBE 

TARGET 

PLATE 

WITH  ORDI- 

WITH 

GRAPH 

TO  FILM 

NARY  GAS 

COOLIDGE 

OR  PLATE 

X-RAY  TUBE 

TUBE 

Dental 

Back  up 

15  inches 

Eastman 

About  60 

8/10  of  that 

Intra-Oral 

about  5  inches 

slow 

Milliampere 

necessary 

parallel 

seconds 

with  gas 

spark 

tube 

Dental 

Back  up 

15  inches 

Eastman 

About  15 

8/10  of  that 

Intra-Oral 

about  5  inches 

fast 

milliampere 

necessary 

parallel 

seconds,    (about 

with  gas 

spark 

Mthe 

tube 

Penetrometer 

exposure 

Benoist 

necessary  for 

about  5 

slow  films) 

Dental 

Back  up 

18  inches 

Paragon 

About  90 

8/10  of  that 

Extra-Oral 

about  5  inches 

Milliampere 

necessary 

parallel 

seconds 

with  gas 

spark 

tube 

Penetromet  r 

Benoist 

about  5 

Frontal 

Back  up 

20  inches 

Paragon 

About  200 

8/10  of  that 

Sinuses, 

about  =)}/2 

Milliampere 

necessary 

Ethmoids, 

parallel 

seconds.      (This 

with  gas 

Antra,  also 

spark 

milliampere- 

tube 

Sphenoids 

Penetrometer 

second 

and 

Benoist 

exposure 

Mastoids 

about  6 

can  be 

reduced  to  14, 

or  less 

by  the  use  of  an 

intensifying 

screen) 

356 


APPENDIX 


It  is  of  passing  interest  to  compare  the  dental  milliampere-second 
table  with  a  milliampere-second  table  for  other  parts  of  the  body.* 
(After  Geo.  W.  Brady.) 


KIND  OF 
RADIO- 
GRAPH 

CONDITION 
OF  TUBE 

DISTANCE 

FROM 

TARGET 

TO  PLATE 

MAKE  OF 
PLATE 

TIME  OF 
EXPOSURE 

WITH  ORDI- 
NARY GAS 

X-RAY  TUBE 

TIME  OF 
EXPOSURE 

WITH 
COOLIDGE 

TUBE 

Hand 

Back  up 

about  53^ 

inches  of 

parallel 

spark 

1 8  inches 

Paragon 

i8M.  A.  S. 

A    the 

exposure 

necessary 

with  gas 

tubes 

Wrist,  lateral 

Ditto 

Ditto 

Ditto 

27  M.  A.  S. 

Ditto 

Elbow 

Ditto 

Ditto 

Ditto 

35  M.  A.  S. 

Ditto 

Ankle,  lateral 

Ditto 

Ditto 

Ditto 

44  M.  A.  S. 

Ditto 

Ankle, 
antero- 
posterior 

Ditto 

Ditto 

Ditto 

62  M.  A.  S. 

Ditto 

Knee,  lateral 

Ditto 

Ditto 

Ditto 

62  M.  A.  S. 

Ditto 

Knee, 
antero- 
posterior 

Ditto 

Ditto 

Ditto 

70M.A.  S. 

Ditto 

Shoulder 

Ditto 

Ditto 

Ditto 

105  M.  A.  S. 

Ditto 

Kidney 

Ditto 

Ditto 

Ditto 

175  M.  A.  S. 

Ditto 

*Size  of  patient:  160  lbs. 


tb«  Explanation  of  the  The  beginner  in  radiodontic  work  is  very  much 

InwVl  xffi"inacbin<^^^  surprised  and  confused  when  he  learns  that  Dr.  A., 
*  who  has  a  large,  powerful  and  elaborate  X-ray  outfit 
"  exposes  his  dental  films  5  seconds,"  while  Dr.  B.,  who  has  a  very 
small  outfit  "  exposes  his  dental  films  only  i  second."  The  explanation 
is  that  Dr.  A.  is  using  a  tube  which  backs  up  only  about  3  inches  of 
parallel  spark,  while  Dr.  B.'s  tube  backs  up  5  inches,  or  more.  Dr.  A.'s 
target-film  distance  is  16  or  20  inches,  while  Dr.  B.'s  target-film  distance 
is  about  5  inches.  Dr.  A.  could,  by  using  a  tube  of  higher  vacuum  and 
lessening  his  target-film  distance,  reduce  his  time  of  exposure,  but  his 
negatives  would  not  be  as  good ;  they  would  not  be  beautifully  and  bril- 
liantly black  and  white,  but  would  become  darker,  less  contrasty,  less  dis- 
tinct, less  perfect. 

The  practice  of  reducing  the  time  of  exposure  for  dental  negatives 
may  easily  be  carried  to  the  point  where  the  quality  of  the  negative  is 
sacrificed. 

It  is  impossible  to  make  a  dental  radiograph  with  a  short  exposure 
with  some  X-ray  machines  of  the  transformer  type,  because  they  do  not 
produce  sufficient  voltage  to  excite  a  high  vacuum  tube.  Thus  some 
owners  and  operators  of  such  transformer  machines  are  greatly  disturbed 
because  their  neighbor,  who  has  an  induction  or  Tesla  coil,  does  not  find 
it  necessary  to  expose  so  long.  Such  operators  should  be  consoled  by 
observing  that  they  produce  negatives  of  a  finer  quality;  their  type  of 
machine  is  protecting  them  against  the  mistake  of  sacrificing  quality  for 
speed  exposures. 


APPENDIX  TO  CHAPTER  VI. 

The  following  is  abstracted  from  an  editorial  by  Dr. 
'^'''cdWa?"'*  ^"   ^'   Jol^^son,   which   was  published  in  the   May, 

1914,  edition  of  the  Dental  Review: 

the  Tallibilitv  of  tbe  X-Ray. 

"  It  is  probably  true  that  no  other  discovery  in  recent  years  has  been 
of  greater  value  to  the  medical  and  dental  profession  than  has  that  of 
the  X-ray.  It  has  aided  us  in  clearing  up  many  obscure  lesions  and  has 
thus  been  of  immense  value  in  diagnosis.  In  dentistry  it  has  been  of  espe- 
cial service  in  discovering  impacted  or  delayed  teeth  in  the  jaws,  and  has 
shed  light  on  many  a  puzzling  case  of  neuralgia  by  showing  the  cause  of 
the  irritation.  Although  it  is  only  a  comparatively  few  years  since  its 
introduction  it  would  leave  us  bereft  of  much  of  our  usefulness  if  it  were 
eliminated  from  our  practice. 

"  And  yet  with  all  this  it  has  its  limitations  and  it  is  high  time  they 
were  pointed  out.  It  has  been  used  extensively  for  diagnosing  abscesses 
and  bone  lesions  in  the  jaws  and  for  showing  the  condition  of  root  fillings 
in  teeth.  It  is  useful  for  these  purposes  up  to  a  certain  point,  but  it  is 
by  no  means  infallible  and  in  some  cases  it  is  decidedly  misleading.  It 
may  be  that  we  have  not  yet  advanced  sufificiently  in  its  use  to  correctly 
interpret  its  findings,  but  the  fact  is  that  when  it  comes  to  diagnosing 
bone  absorptions  and  alveolar  abscesses  the  most  expert  X-ray  men  we 
have  are  often  very  wide  of  the  mark.  Nor  do  we  believe  this  can  be 
relied  on  to  tell  accurately  whether  root  canals  are  properly  filled  or  not. 
Many  a  pulpless  tooth  has  been  arraigned  as  the  culprit  when  the  fault 
lay  elsewhere  and  many  an  operator  has  been  censured  for  poor  root 
filling  when  his  operation  was  not  at  fault.  And  the  great  danger  is  that 
medical  men  will  be  extensively  misled  about  dental  operations  as  inter- 
preted by  the  X-ray.  Already  some  of  them  are  reading  all  sorts  of 
disaster  as  the  result  of  root  filling.  If  a  patient  has  a  pain  somewhere 
about  the  jaws  they  are  making  X-rays — which  in  itself  is  perfectly 
proper,  and  which  in  many  instances  will  throw  light  on  the  trouble — 
but  they  are  reading  into  these  X-rays  much  evidence  which  is  not  com- 
patible with  fact.  It  does  not  follow  that  because  a  radiograph  shows  a 
dark  area  around  the  end  of  a  root  that  the  bone  is  all  absorbed  at  that 

357 


358  .  APPENDIX 

point  or  that  there  is  an  abscess  cavity  there.  It  does  not  prove  thai  a 
root  canal  is  not  well  filled  because  the  radiograph  fails  to  show  a  filling 
to  the  apex.  We  must  be  more  discriminating  in  reading  radiographs 
than  we  have  been  in  the  past  if  we  are  to  avoid  doing  harm  to  the 
patient. 

"  A  single  instance,  illustrative  of  many  others  which  might  be  men- 
tioned, will  serve  to  prove  the  present  contention.  A  patient  had  pain 
in  the  region  of  the  left  upper  cuspid.  This  tooth  was  banded  as  the 
middle  pier  to  a  bridge.  A  radiograph  was  made  of  the  region,  and  the 
verdict  of  the  radiographer  was  that  there  was  an  extensive  abscess 
cavity  around  the  cuspid  with  the  bone  all  absorbed.  His  remark  was : 
'  If  you  cut  the  band  the  cuspid  will  drop  out.  Nothing  holds  it  in  place 
but  the  gold  band.' 

"  The  band  was  cut  and  the  cuspid  was  found  perfectly  firm — the 
thing  that  nearly  dropped  out  was  the  bridge,  the  cuspid  having  been  its 
chief  support.  Thinking  from  the  evidence  of  the  radiograph  that  there 
must  at  least  be  an  abscess  on  the  cuspid  it  was  drilled  into — only  to  find 
a  live  pulp.  Here,  with  the  best  intentions,  a  wrong  was  done  the  patient, 
on  the  evidence  of  the  X-ray,  and  it  is  probably  not  an  isolated  case. 

"  This  article  is  not  intended  as  a  reflection  on  the  great  utility  of 
the  X-ray,  which  is  cheerfully  acknowledged,  but  merely  to  counsel 
caution  on  the  part  of  those  who  invariably  *  see  things  '  in  every  radio- 
graph that  is  taken." 

HbStfact  from  tbC       The  writer's  answer  to  Dr.  Johnson's  editorial  which 
Dr?  Johnson's  ^^^  pubHshed  in  the  June,  1914,  issue  of  the  Dental 

editorial*  Review  is  now  given  : 

Indianapolis,  Ind.,  April  9th,  1914. 
My  dear  Dr.  Johnson  : 

Your  editorial,  "  The  Fallibility  of  the  X-Rays,"  creates  in  me  a 
degree  of  cerebral  unrest  which,  reduced  to  ink  and  paper,  is  as  follows: 

First,  let  me  say  I  agree  with  practically  everything  you  say,  and  I 
am  gratified  to  have  you  take  such  comprehensive  editorial  notice  of  the 
matter.  I  agree  with  practically  everything  you  say,  and  yet,  if  I  were 
writing  on  the  subject,  my  title  would  be  "  The  Infallibility  of  the 
X-Rays  "  instead  of  "  The  Fallibility  of  the  X-Rays." 

That  the  radiograph  has  its  "  limitations  "  and  that  it  is  sometimes 
"  decidedly  misleading  "  I  grant  you,  but  it  is  absolutely  infallible ;  i.  e., 
incapable  of  error.  It  is  always  the  product  of  definite  physical  and 
chemical  laws. 


READING    RADIOGRAPHS  359 

You  say  "  it  may  be  that  we  have  not  yet  advanced  sufficiently  in  its 
use  to  correctly  interpret  its  findings."  There  you  hit  it.  The  apparent 
fallibility  of  the  radiograph  lies  in  our  interpretation  of  it,  in  our  lack 
of  attainable  knowledge  which  would  explain  "  decidedly  misleading " 
appearances ;  and,  in  our  unwillingness  to  admit  that  it  does  have  "  limi- 
tations." 

You  cite  an  illustrative  case.  Allow  me  to  cite  one  also ;  a  case 
which  I  handled  a  number  of  years  ago  when  very  little  dental  radio- 
graphic work  was  being  done  and  it  was  an  "  event  "  to  make  an  "  X-ray 
picture  of  the  teeth."  A  patient  suffering  from  neuralgia  was  sent  to  me 
for  radiographic  examination.  I  found  a  shadow  in  the  region  of  the 
pulp  chamber  of  a  lower  molar  and  made  a  diagnosis  of  pulp  stone.  The 
next  day  the  man  who  referred  the  case  indignantly  informed  me  by 
'phone  that,  on  the  strength  of  my  diagnosis,  he  had  opened  the  molar 
tooth  and  there  was  no  pulp  stone  in  it. 

With  no  further  explanation  you  would  count  this  case  as  one  demon- 
strating the  fallibility  of  the  radiograph.  But  then,  as  I  have  said,  the 
radiograph  is  infallible ;  it  is  always  the  product  of  definite  physical  and 
chemical  laws.  Why  then,  was  there  a  shadow  in  the  region  of  the  pulp 
chamber  of  the  lower  molar  ?  Something  made  that  shadow.  What  was  it  ? 
Perhaps  an  air  bubble  attached  itself  to  the  film  at  the  time  of  its  develop- 
ment. That  would  cause  a  spot.  But  the  shadow  I  saw  did  not  have  the 
characteristic  appearance  of  an  air  bubble  spot,  and,  in  further  disproof 
of  the  air-bubble  explanation,  the  spot  occurred  on  two  different  nega- 
tives in  exactly  the  same  place.  I  asked  to  see  the  patient  again  and, 
upon  examination,  found  a  filling  on  the  buccal  surface,  at  the  gingival 
line.  I  had  mistaken  the  shadow  cast  by  the  cement  filling  for  a  pulp 
stone. 

It  was  my  mistake.  The  radiograph  had  done  what  it  may  be  de- 
pended upon  to  do ;  it  had  unerringly  recorded  densities. 

You  may  ask  if  a  man  is  not  always  liable  to  make  the  same  mistake 
I  made.  No.  Once  his  attention  is  directed  to  the  possibility  of  such  an 
error  he  should  never  make  it. 

And  so  one  may  trace  the  mistakes  in  his  radiographic  diagnosis, 
from  the  radiograph,  to  the  man  who  read  the  radiograph,  in  all  cases 
where  mistakes  have  been  made.  You  mention  the  most  productive  cause 
of  mistakes  when  you  close  your  editorial  by  saying,  "  This  article  is  not 
intended  as  a  reflection  on  the  great  utility  of  the  X-ray,  which  is  cheer- 
fully acknowledged,  but  merely  to  counsel  caution  on  the  part  of  those 
who  invariably  *  see  things  '  in  every  radiograph  that  is  taken." 


36o  APPENDIX 

As  a  man  who  has  worked  to  develop  the  field  of  dental  radiography, 
I  feel  grateful  to  you  for  the  remark,  for  the  greatest  menace  to  a  more 
general  use  of  the  radiograph  is  the  radiographer  who  never  says,  "  this 
radiograph  shows  us  nothing."  The  radiograph  is  the  most  efficient  diag- 
nostic aid  at  our  command,  but  it  does  not  always  enable  us  to  make  a 
diagnosis.  Radiographers  must  admit  this  and  quit  reading  a  definite 
diagnosis  in  every  radiograph,  whether  it  is  there  or  not,  else  men  like 
you.  Dr.  Johnson,  will  blame  the  radiograph  for  the  fallibility  of  the 
radiographer.  H.  R.  R. 

In  further  general  consideration  of  this  subject  I  quote  from  my 
report  to  the  Sixth  International  Dental  Congress,  London,  1914: 

"  I  cannot  consider  the  subject  of  the  advantages  of  radiography 
as  an  aid  to  diagnosis  without  calling  attention  to  the  fact  that  the  good 
derived  from  its  use  depends  very  much  on  the  manner  in  which  it  is 
used.  It  is  unfortunate  that  it  is  not  always  used  in  vain  by  the  man  who 
has  no  idea  of  the  etiology  of  the  patient's  malady,  and  makes,  or  has 
made,  radiographs,  expecting  them  to  reveal,  as  on  a  written  page,  the 
disease,  its  exciting  cause  and  a  paragraph  or  two  describing  treatment. 
I  say  it  is  unforunate  that  the  radiograph  does  not  always  disappoint 
this  man  who  expects  too  much  of  it,  who  forgets  all  other  methods  of 
diagnosis  and  lazily  depends  on  the  radiograph  to  do  all  his  diagnostic 
work  for  him.  It  is  unfortunate  because  it  leads  men  to  believe  that  the 
radiograph  has  arrived  to  replace  all  other  means  and  modes  of  diagnosis, 
when  in  reality  it  has  come  not  to  take  the  place  of,  but  to  take  its  place 
with,  the  probe,  the  history,  the  symptoms,  the  signs,  and  diagnostic  tests. 

"  A  tentative  diagnosis  should  always  be  made  before  the  case  is 
radiographed.  Thus,  for  example,  from  the  signs  and  symptoms,  you 
suspect  an  impacted  tooth.  Radiographs  are  made  to  verify  or  disprove 
this  diagnosis.  If  the  diagnosis  is  verified  by  the  radiograph  a  great 
element  of  doubt  as  to  the  correctness  of  this  diagnosis  is  removed  from 
the  diagnostician's  mind.  If  the  tentative  diagnosis  is  disproved  by  the 
radiograph,  an  important  step  has  been  made  in  diagnosis  by  elimination. 

"  Another  example :  from  signs,  symptoms,  probing  and  tests  we 
make  a  diagnosis  of  alveolar  abscess  of  an  upper  cuspid  tooth. 

"  A  radiograph  is  made,  and  we  learn  that  we  have  not  only  an 
abscess  of  the  cuspid  but  of  the  first  bicuspid  also.  The  radiograph  has 
verified  our  diagnosis  and  elaborated  on  it. 

"  To  epitomize :  if  you  would  derive  the  greatest  benefits  from  the 
radiograph,  use  it  only  to  verify,  or  disprove,  and  elaborate  on  tentative 
diagnoses." 


READING    RADIOGRAPHS  361 

No  set  of  rules  can  be  given  which  will  prevent  mis- 
Jl  Ei$t  Of  lUfSfaUW,     takes  in  judgment  rendered  from  radiographic  read- 
ings.    However,  as  I  have  said  elsewhere,  the  radio- 
graph is  no  mere  fad — it  is  here  to  stay — and  so  it  is  well  that  we  should 
learn  as  soon  as  possible  the  mistakes  one  engaged  in  radiodontic  work 
is  liable  to  make.    Accordingly  the  following  list  is  given. 

It  is  incomplete,  as  perforce  any  list  of  mistakes  in  radiographic 
interpretation  must  be,  for  someone  is  making  some  new  mistake  every 
day. 

The  List: 

( I )  To  mistake  the  mental  foramen  for  an  abscess  cavity  at  the  apex 
of  a  lower  bicuspid.  (2)  To  mistake  the  anterior  palatine  foramen  for 
an  abscess  cavity.  (3)  To  mistake  the  nasal  cavity  for  necrosis  of  the 
palate.  (4)  To  mistake  the  maxillary  sinus  for  an  abscess  cavity  at  the 
apices  of  the  upper  bicuspids  and  molars.  (5)  To  mistake  the  inferior 
dental  canal  for  a  fistulous  tract.  (6)  To  mistake  the  mandibular  fora- 
men for  osteoporosity,  due  to  disease.  (7)  To  fail  to  bear  in  mind 
that  there  is  such  a  thing  as  a  normal  periapical  space.  (8)  To  mistake 
a  dark  spot,  due  to  somewhat  unusual  porosity,  for  an  alveolar  abscess. 
(9)  To  mistake  a  shadow  caused  by  the  spinal  column  for  necrosis  of  the 
mandible.  (10)  To  mistake  the  lingual  tubercle  for  a  bone  whorl  or  the 
shadows  on  either  side  of  the  lingual  tubercle  for  osteoporosity  due  to 
infection.  (11)  To  mistake  the  hyoid  bone  for  "  some  "  pathologic  lesion. 
(12)  To  mistake  the  larynx  for  an  abscess  cavity  in  the  neck.  (13)  To 
make  a  diagnosis  of  antral  empyema  because  one  antrum  happens  to  be 
smaller  than  the  other.  (14)  To  mistake  the  coronoid  process  for  the 
root  of  a  third  molar.  (15)  Without  taking  into  account  the  angle  at 
which  the  X-rays  were  directed  toward  the  tooth  and  film,  to  assume  that 
a  canal  filling  does  not  reach  the  apex  of  a  root  when  it  does.  (16) 
Without  taking  into  account  the  angle  at  which  the  X-rays  were  directed 
toward  the  tooth  and  film,  to  assume  that  the  buccal  roots  of  upper 
,  bicuspids  and  molars  are  much  shorter  than  the  lingual  roots  of  the  same 
teeth.  (17)  To  assume  that  a  perforation  through  the  side  of  a  root 
does  not  exist  because  it  cannot  be  seen  to  the  mesial  or  distal.  (18)  To 
assume  that  a  broach  is  following  a  canal  because  it  cannot  be  seen 
extending  too  far  to  the  mesial  or  distal.  (19)  To  mistake  a  canal  filling 
passing  into  a  crooked  root  for  a  canal  filling  material  passing  through  a 
perforation  through  the  side  of  the  root.  (20)  To  state  definitely  from 
the  appearance  of  flat  radiographs  (not  stereoscopic  radiographs)  that 
impacted  teeth  lie  to  the  lingual  or  facial  of  the  other  teeth.  (21)  To 
mistake  a  small  cervical  filHng  for  a  pulp  stone.     (22)  To  assume  that  a 


362  APPENDIX 

filling  in  the  crown  of  a  tooth  enters  the  pulp  chamber  when  it  does  not. 
{2T,)  To  assume,  from  the  appearance  of  flat  radiographs  (not  stereo- 
scopic radiographs)  that  the  root  of  an  upper  posterior  tooth  penetrates 
the  antrum.  (24)  To  fail  to  take  into  account  that  an  abscess  cavity  may 
lap  to  the  lingual  or  facial  of  the  adjoining  teeth  giving  the  radiographic 
appearance  of  their  involvement  but  without  involving  them.  (25)  To 
fail  to  consider  the  element  of  depth  when  judging  the  size  of  an  abscess 
cavity.  (26)  To  mistake  normal  resorption  of  bone,  due  to  age,  for 
pyorrhea  alveolaris.  (27)  To  fail  to  take  into  account  the  effect  the  tip- 
ping of  a  tooth  to  the  lingual  or  facial  will  have  on  the  appearance  of  the 
tooth  in  the  radiograph.  (28)  To  state  definitely  that  a  rarefied  area 
at  the  apex  of  a  root  represents  infection  without  considering  the  anatomy 
of  the  parts  and  the  symptoms  and  history  of  the  case.  (29)  To  state 
that  no  infection  exists  because  no  abscess  cavity  can  be  observed.  (30) 
To  fail  to  bear  in  mind  that  osteodensity  as  well  as  osteoporosity  may  be 
caused  by  infection.  (31)  To  assume,  when  observing  an  abscess  cavity 
at  the  apex  of  a  tooth  with  a  well-filled  canal,  that  the  abscess  occurred 
after  canal  filling.  (32)  To  expect  to  see  a  fistulous  tract.  (33)  To  give 
a  positive  diagnosis  of  pulp  stones  from  the  appearance  of  one  radio- 
graph. (34)  To  try  to  make  one  radiograph  do  the  work  of  two  or 
several.  (35)  To  mistake  hypercementosis  for  a  poorly  made  radio- 
graph. (36)  Not  to  know  the  difference  between  a  good  radiograph 
and  a  poor  one.  (37)  To  make  just  one  radiograph  of  a  part  and  stop, 
calling  it  a  radiographic  examination.  (38)  To  depend  on  intra-oral 
radiographs  alone,  especially  in  cases  of  neuralgia,  facial  fistula,  impacted 
third  molars,  and  abscess  of  the  lower  bicuspids.  (39)  To  fail  to  use  a 
reading-glass  when  studying  negatives  and  so  avail  one's  self  of  the  great 
assistance  rendered  by  the  practice.  (40)  To  fail  to  use  the  electric  test 
for  vitality  of  pulps  in  connection  with  radiographic  examinations.  (41 ) 
To  make  radiographs  of  every  tooth  in  the  mouth  in  all  cases  where  the 
teeth  are  being  examined  to  locate  foci  of  infection. 

We  will  now  proceed  with  a  short  consideration  of  each  of  the  fore- 
going mistakes : 

I.  To  Mistake  the  Mental  Foramen  for  an  Abscess  Cavity  at 
Apex  of  a  Lower  Bicuspid. 

Figure  392  shows  the  mental  foramen.  The  location  of  this  foramen 
varies  greatly  in  different  individuals.  It  may  occur  in  such  a  position  in 
a  radiograph  as  to  have  the  appearance  of  an  abscess  cavity  at  the  apex 
of  the  second  or  first,  lower  bicuspid  (Fig.  393).  When  the  radiograph 
is  made  on  a  small  film  held  in  the  mouth  and  the  rays  have  been  directed 
from  below  upward  this  is  especially  likely  to  occur. 


READING    RADIOGRAPHS 


363 


-TT 


Fig.   392.      The  mental  foramen  below  and  between  the  apices  of  the  roots  of  the  lower  bicus- 
pids.    (Radiograph  by  Cole  and  Beeler,  Indianapolis.) 


Fig.  393.      The  mental   foramen  at  the   apex   of   the   lower  second  bicuspid,   having  the   appear- 
ance of  abscess  cavity. 


3^4 


APPENDIX 


Plates  are  better  than  films  to  differentiate  between  the  mental  fora- 
men and  an  abscess  cavity  because  the  radiographic  shadows  on  them  are 
less  likely  to  be  distorted  and  because  they  take  in  a  greater  field  for 
observation.  In  a  plate  one  can  see  both  the  mental  foramen  and  the 
abscess  cavity  if  one  exists.  If  a  spot  having  the  appearance  of  an  abscess 
cavity  is  observed  at  the  apex  of  a  lower  bicuspid  and  the  mental  foramen 


Fig.  394.  The  anterior  palatine 
foramen  having  the  appear- 
ance of  an  abscess  cavity  at 
the  apex  of  an  upper  centra! 
incisor. 


Fig.  395.  Nasal  cavity  spots 
which  have  been  mistaken 
for  abscesses  of  the  upper 
anterior  teeth  and  necrosis  of 
the  palate. 


Fig.  396.  Shovi^ing  the  antrum  which  is  sometimes  mistaken  for  an  abscess  of  the  upper  pos- 
terior teeth.     Tlie  shadow  of  the  antrum  may  occur  even  as  far  forward  as  the  apical  region  of 

the  cuspid.     Fig.  459A.) 

cannot  be  observed  elsewhere,  in  a  large  extra-oral  radiograph,  it  is  prob- 
able that  the  spot  at  the  apex  of  the  tooth  is  the  mental  foramen.  The 
tooth  should  be  tested  with  the  electric  test,  for  pulp  vitality,  if  possible. 
If  this  test  cannot  be  made,  an  exploratory,  diagnostic  opening  may  be 
made  into  the  tooth  of  sufficient  depth  to  ascertain  whether  or  not  the 
pulp  is  vital. 

2.  To  Mistake  the  Anterior  Palatine  Foramen  for  an  Ab- 
scess Cavity. 

Figure  394  shows  the  anterior  palatine  foramen.     Depending  on  the 


READING    RADIOGRAPHS 


365 


angle  of  the  rays  and  the  position  of  the  film,  this  foramen,  which  is  in 
the  region  of  the  apices,  and  between  the  roots,  of  the  upper  central 
incisors,  may  have  the  radiographic  appearance  of  an  abscess  cavity  at  the 
apex  of  one  of  the  central  incisors. 

3.  To  Mistake  the  Nasal  Cavity  for  Necrosis  of  the  Palate. 
Figure  395  shows  nasal  cavity  spots  which  have  been  mistaken  for 

abscesses  of  the  upper  anterior  teeth  and  necrosis  of  the  palate. 

4.  To  Mistake  the  Maxillary  Sinus  for  an  Abscess  Cavity  at 
the  Apices  of  the  Upper  Bicuspids  and  Molars. 

Figure  396  illustrates  the  appearance  of  the  antrum  which  is  some- 
times mistaken  for  a  large  abscess  cavity.  It  is  sometimes  difficult,  to  the 
point  of  being  impossible,  to  differentiate  between  the  antrum  and  an 
abscess  cavity  by  the  study  of  radiographs  alone;  use  the  electric  test  for 
pulp  vitality.     See  diagram  Fig.  397.     (See  Fig.  459A.) 


Fig.  397. 


Diagram  showing  why  the  shadow  of  the  antrum  occurs  at  the  apices  of  the  roots  of 
the  upper  posterior  teeth. 


5.  To  Mistake  the  Inferior  Dental  Canal  for  a  Fistulous 
Tract. 

Figure  398  shows  the  inferior  dental  canal  leading  forward  from  the 
unerupted  third  molar.    This  canal  was  mistaken  for  a  fistulous  tract. 

6.  To  Mistake  the  Mandibular  Foramen  for  Osteoporosity, 
Due  to  Disease. 

At  the  mandibular  foramen  the  ramus  is  thin  and  so  this  area  may 
appear  dark  in  the  radiographic  negative. 


366  APPENDIX 

7.  To  Fail  to  Bear  in  Mind  That  There  is  Such  a  Thing  as  a 
Normal  Periapical  Space. 

It  should  constantly  be  borne  in  mind  that  there  is  such  a  thing  as  a 
normal  periapical  space  and  that  this  space  may  be  much  larger  in  some 
cases  than  in  others.  A  large  periapical  space  has  about  the  same  appear- 
ance as  a  small  abscess  cavity.  To  differentiate  between  a  small  abscess 
cavity  and  a  large  periapical  space  learn  whether  or  not  the  pulp  of  the 


Fig.   398.      The  inferior  dental  canal  leading  forward  from  the  apical  region  of  the  lower  third 
molar.     It  was  mistaken  for  a  fistulous  tract. 

tooth  is  vital  by  the  electric  test  or  by  making  an  exploratory  opening.  In 
this  connection  I  may  say  that  infection  may  cause  hypercementosis  and 
abnormal  osteodensity,  i.e.,  osteosclerosis,  in  the  region  of  the  infection, 
which  knowledge  will  assist  in  differentiating  between  small  abscess  cavi- 
ties and  normal,  large  periapical  spaces.  Figure  399  illustrates  an  un- 
usually large  periapical  space  at  the  roots  of  a  lower  molar  while  Fig. 
400  illustrates  a  small  abscess  cavity  no  larger  than  a  large  periapical  space 
at  the  apices  of  the  lower  third  molar.  The  filling  material  seen  to  enter 
the  pulp  chamber  admits  of  a  differential  diagnosis  in  this  latter  case. 
(See  Fig.  444,  which  is  the  same  as  Fig.  400  but  shows  the  filHng  in  the 
pulp  chamber  much  better.) 

8.  To  Mistake  a  Dark  Spot,  Due  to  Somewhat  Unusual 
Porosity,  for  an  Alveolar  Abscess. 

Figure  401  shows  what  seems  to  be  an  abscess  at  the  apex  of  the 


READING    RADIOGRAPHS 


367 


distal  root  of  a  lower  molar.  Figure  402,  however,  of  this  same  tooth, 
made  at  a  different  angle,  shows  this  spot  to  be  simply  a  cancelous  spot 
in  the  bone. 

Some  men  have  a  tendency  to  call  any  dark  area  in  a  radiographic 
negative  an  abscess.  Figures  401  and  402  show  how  careful  one  must  be 
not  to  mistake  a  normal  dark  spot  for  a  pathologic  one.    The  bone  is  nor- 


Fig.  399.  Unusually  large  periapical 
space  at  the  apex  of  the  roots  of  the 
lower  molar;  appearance  similar  to 
that  of  a  very  small  abscess. 


Fig.  400.  Very  small  abscess  at  apices  of  roots 
of  lower  third  molar;  appearance  similar  to 
that  of  large  periapical  space. 


Fig.  401.  Spot  at  the  apex  of  the 
distal  root  of  the  anterior  lower 
molar;    has    the    appearance    of    an 

abscess. 


Fig.  402.  Same  as  Fig.  401,  taken  at 
a  different  angle.  The  spot  shows 
now  as  a  cancelous  area  to  the  distal 
of  the  apex  of  the  distal  root  of  the 
anterior   molar. 


mally  much  more  cancelous  in  some  individuals  than  in  others,  and  the 
same  bone  may  be  more  cancelous  in  some  regions  than  in  others. 

Figure  403  shows  suspicious  (?)  areas  in  the  apical  region  of  the 
central  and  lateral  incisors.  These  areas  are  the  nostrils,  which  may  be 
mistaken  for  bone  rarefication,  due  to  infection.  It  is  unlikely  that  the 
half-tone  will  show  it  well,  but  the  original  negative  of  Fig.  403  shows  the 
outline  of  the  end  of  the  nose  distinctly. 

9.  To  Mistake  a  Shadow  Caused  by  the  Spinal  Column  for 
Necrosis  of  the  Mandible. 


368 


APPENDIX 


Figure  404  shows  overlapping  of  the  ramus  and  the  spinal  column  in 
such  a  manner  as  to  give  the  ramus  the  appearance  of  being  diseased  to 
one  not  proficient  in  the  reading  of  radiographs.  I  recall  also  a  case  in 
which  the  shadow  of  a  vertebra  was  mistaken  for  an  unerupted  tooth  in 
the  ramus. 

10.  To  Mistake  the  Lingual  Tubercle  for  a  Bone  Whorl  or 
THE  Shadows  on  Either  Side  of  the  Lingual  Tubercle  for  Osteo- 
POROSITY,  Due  to  Infection. 


Fig.  403.  Radiograph  showing 
the  tip  of  the  nose  and  the 
two  nostrils,  which  latter  have 
somewhat  the  appearance  of 
abscesses  of  the  lateral  in- 
cisors.     (Retouched.) 


Fig.   404.      Superimposition    of   the   spinal   column   and   the   man- 
dible, giving  the  latter  an  abnormal  appearance. 


Figure  405  shows  the  lingual  tubercle,  as  it  sometimes  appears  in 
radiographs,  simulating  the  appearance  of  a  bone  whorl. 

11.  To  Mistake  the  Hyoid  Bone  for  "Some"  Pathologic 
Lesion. 

The  hyoid  bone,  especially  when  it  and  the  mandible  overlap,  is  some- 
times thought  to  represent  some  abnormal  condition  of  the  mandible  or 
the  neck.  The  hyoid  bone  can  be  seen  below  the  mandible  in  Figs.  255 
and  287. 

12.  To  Mistake  the  Larynx  for  an  Abscess  Cavity  in  the 
Neck. 

The  larynx  will  appear  as  a  dark  area  in  the  radiographic  negative 
and  should  not  be  mistaken  for  a  pathologic  lesion. 


READING    RADIOGRAPHS 


369 


13,  To  Make  a  Diagnosis  of  Antral  Empyema  Because  One 
Antrum  Happens  to  Be  Smaller  Than  the  Other. 

It  should  be  borne  in  mind  that  one  antrum  may  be  much  smaller 
than  the  other  and,  if  the  radiographer  does  this,  he  will  not  mistake  a 
small  antrum  for  a  diseased  one  just  because  it  happens  to  be  smaller  than 
its  mate  on  the  opposite  side. 

14.  To  Mistake  the  Coronoid  Process  for  the  Root  of  a  Third 
Molar. 


Fig.   406.      Case   in   which   the  coronoid 

process  was  mistaken  for  a  root  of 

an  upper  third  molar. 


Fig.  405.     Radiograph  of  the 
lingual  tubercle. 


Fig.    407.      In   this   bicuspid,    one   canal 

filling  seems  to  reach  farther  than 

the    other. 


Fig.   408.      Same  bicuspid,   same 

canal  fillings  illustrated  in 

Fig.   407. 


Figure  406  is  a  radiograph  of  a  case  in  whicn  the  coronoid  process 
was  mistaken  for  a  root  of  an  upper  third  molar. 

15,  Without  Taking  Into  Account  the  Angle  at  Which  the 
X-RAYS  Were  Directed  Toward  the  Tooth  and  Film,  to  Assume 
That  a  Canal  Filling  Does  Not  Reach  the  Apex  of  a  Root  When 
IT  Does. 

Figure  407  is  an  experimental  case.     In  Fig.  407  one  canal  filling 


370 


APPENDIX 


reaches  the  end  of  the  excised  bicuspid  root  while  the  other  seems  to  fall 
short  of  the  end.  Figure  408  is  of  the  same  bicuspid,  removed  from  the 
alveolus,  and  shows  that  both  canal  fillings  reach  the  end  of  the  resected 
root. 

Figure  409  diagrammatically  illustrates  why  one  canal  filling  has  the 
appearance  of  not  reaching  as  far  as  the  other  in  Fig.  407. 


Fig.   409.      Diagram   explanatory   of  Figs.   407   and  408.      A,   where   the  shadow   of   the   end  of 

the  canal  filling  m  the  lingual  canal  is  cast  on  film.      B,   where  shadow  of  the  end  of  the  canal 

filling  in  the  buccal  canal  is  cast  on  film. 


Fig 


410.      One  canal  filling  seems  too  short 
and  to  pass  to  the  distal  too  far. 


Fig.  411.     Same  as  Fig  410  after 
removal  of  bicuspid  from  alveolus. 


Figure  410  shows  one  canal  filling  apparently  reaching  the  end  of 
the  root  while  the  other  falls  a  little  short.  However,  observe  Fig.  411, 
which  is  of  the  same  tooth  removed  from  the  mouth. 

Figure  412  diagrammatically  illustrates  how  the  buccal  canal  is 
thrown  to  the  mesial  or  distal  of  the  lingual  canal  in  Figs.  407  and  410. 
By  directing  the  rays  mesio-lingually  (X-rays  No.  i  of  Fig.  412),  the 
buccal  canal  is  thrown  to  the  mesial:  Fig.  407.     By  directing  the  rays 


READING   RADIOGRAPHS 


371 


disto-lingually  (X-rays  No.  2  of  Fig.  412),  the  buccal  canal  is  thrown  to 
the  distal:  Fig.  410. 


Fig.  412.  Cross  sec- 
tion of  an  upper  bi- 
cuspid tooth  show- 
ing how  the  buccal 
canal  may  be 
thrown  to  the  me- 
sial (X-rays  No.  1), 
or  the  distal  (X- 
rays  No.  2),  of  the 
lingual  canal.  With 
the  rays  passing 
through  the  tooth  as 
indicated  by  "  X- 
rays  No.  3,"  the 
shadows  of  the 
buccal  and  lingual 
canals  lie  one  on 
the  other  and  ap- 
pear as  one  in  the 
radiograph. 


BUCCAL  CANAL 


LIN61/AL  CANAL  \ 


Fig.  413.  Showing  how 
the  angle  of  the  X- 
rays  may  cast  the 
shadow  of  a  canal  fill- 
ing reaching  the  end 
of  the  root  so  the  fill- 
ing has  the  radio- 
graph appearance  of 
reaching  the  end  in 
one  instance  and  of 
failing  to  reach  the 
end  in  the  other 
•  'AB." 


A 
B 


Fig.  414.  Showing 
how  the  location  of 
the  apical  foramen 
may  keep  a  canal 
filling,  which 
reaches  the  end  of 
the  canal,  from 
having  the  radio- 
graphic appearance 
of  doing  so. 


Figure  413  diagramatically  illustrates  how,  by 
figs.  413  and  414.        changing  the  angle  at  which  the  X-rays  are  directed 

through  the  parts  onto  the  film,  a  canal  filling  which 
reaches  the  end  of  the  root  may  appear  to  reach  the  end  or  to  fall  short 
of  reaching  the  end.  With  the  X-rays  directed  as  lines  A  and  B  indicate, 
the  canal  filling,  as  it  appears  on  the  radiograph,  will  not  reach  the  end 
of  the  root ;  with  the  rays  directed  as  indicated  by  the  unmarked  lines,  the 


372 


APPENDIX 


resulting  radiograph  will  show  the  canal  filling  reaching  to  the  end  of 
the  root. 

The  lines  marked  A  and  B  then  may  be  considered  to  represent  an 
incorrect  angle  for  the  X-rays,  while  the  unmarked  lines  represent  the 
correct  angle.  However,  when  the  apical  foramen  happens  not  to  be  in 
the  bucco-lingual  center  of  the  root,  but  stands  somewhat  to  the  buccal, 
what  would  ordinarily  be  the  correct  angle  for  the  rays  will  cast  the  shad- 
ow of  the  canal  filling  short  of  the  extreme  apical  end.    Fig.  414. 


Fig.    415.       Showing    how    the    canal    filling    in    the  mesio-buccal  root  of  a  lower  molar  may 
seem  not  to  reach  the  end  of  the  root  when   it  does. 


Fig.     416.       Showing    how    the    angle    of    the  X-rays  may  make  the  buccal   roots  of  upoer 
molars  seem  much  shorter  than  the  lingual. 

The  thickness  of  the  tooth,  bucco-Hngually,  governs  to  a  o-reat  deo-ree 
the  possibility  of  distortion  in  such  a  manner  as  to  cause  a  canal  filling 
which  reaches  the  end  of  the  root  to  have  the  appearance  of  failino-  to 
do  so.  Thus  the  mesio-buccal  canal  of  lower  molars  as  well  as  the  buccal 
canal  in  upper  bicuspids  is  especially  liable  to  this  distortion  (Fig.  415). 


READING    RADIOGRAPHS 


373 


while  the  more  cone-shaped  roots  (roots  narrow  from  facial  to  lingual  at 
their  apices)  are  almost  free  from  the  liability  of  such  distortion. 

i6.  Without  Taking  Into  Account  the  Angle  at  Which  the 
X-RAYS  Were  Directed  Toward  the  Tooth  and  Film,  to  Assume 
That  the  Buccal  Roots  of  Upper  Bicuspids  and  Molars  Are  Much 
Shorter  Than  the  Lingual  Roots  of  the  Same  Teeth. 

Figure  416  diagrammatically  illustrates  why  the  buccal  roots  some- 
times appear  so  much  shorter  than  the  lingual  roots.  As  the  X-rays  are 
directed  from  a  higher  point  in  a  more  downward  direction  this  distor- 
tion is  increased. 

17.  To  Assume  That  a  Perforation  Through  the  Side  of  a 
Root  Does  Not  Exist  Because  it  Cannot  Be  Seen  to  the  Mesial 
OR  Distal. 

It  is  a  mistake  to  state  that  a  perforation  does  not  exist  because 
it  cannot  be  seen  to  the  mesial  or  distal.  I  have  seen  cases  of  perforation, 
to  the  facial  and  lingual,  with  posts  passing  through  them  which  could 
not  be  observed  radiographically.  In  such  cases  as  these  efforts  may  be 
made  to  show  the  perforation  by  directing  the  rays  through  the  tooth  at 
different  angles,  i.e.,  m^^?o-lingually  and  t^i^^o-lingually.     (Fig.  419B.) 


Fig.   417.      Showing  hole  in  bone  caused  by  abscess  of  lower  second  molar. 

If  the  perforation  itself  cannot  be  observed,  bone  destruction  caused  by 
it  can  sometimes  be  seen. 

In  this  connection  I  direct  your  attention  to  Fig.  417.  Though  the 
teeth  are  missing,  observe  the  hole  in  the  bone  caused  by  a  dento-alveolar 
abscess  of  the  lower  second  molar.  Figure  418  is  a  radiograph  of  Fig. 
417.  Observe  now  that  the  hole  caused  by  the  abscess  is  seen  where  the 
roots  of  the  lower  second  molar  bifurcate.     So  in  the  practice  of  radio- 


374 


APPENDIX 


dontia  the  operator  will  often  find,  when  looking  for  an  abscess  of  a  lower 
molar  (particularly  the  second)  a  dark  area  in  the  region  of  the  bifur- 
cation of  the  roots  and  little  or  no  bone  involvement  at  the  apices  of  the 
roots  of  the  tooth  under  observation.  The  dark  area  in  the  region  of  the 
bifurcation  will  be  looked  upon  as  suspicious  of  a  perforation  through  the 


Fig.   418.      Radiograph  of  Figure  417. 


Fig.  419.     What  seems  to  be  a  post  passing  through  the  side  of  the  root. 


floor  of  the  pulp  chamber  if  the  tooth  is  one  in  which  there  has  been  an 
effort  made  to  open  its  canals.  But  the  liabiHty  of  the  presence  of  a  hole 
in  the  external  alveolar  plate  near  the  region  of  bifurcation  should  not 
be  lost  sight  of.    The  opening  occurs  in  this  region  following  the  path  of 


READING    RADIOGRAPHS 


375 


least  resistance,  the  path  directly  buccally  or  buccally  and  downward 
being  through  the  very  dense  bone  of  the  external  oblique  ridge.  Ab- 
scesses at  the  apices  of  the  lower  molars  often  show  the  dark  area  repre- 
senting the  abscess  indistinctly,  the  negative  having  a  light  haze  thrown 
over  it  due  to  the  density  of  the  oblique  ridges.  Thus  care  must  be  exer- 
cised or  abscess  areas  at  the  apices  of  the  lower  molars — particularly  the 
second  and  third,  will  be  overlooked. 

Figure  419  shows  what  might  easily  be  mistaken  for  a  post  passing 
through  the  side  of  the  root.  Notice,  however,  there  is  no  bone  destruc- 
tion about  the  post  which  seems  to  penetrate  the  osseous  tissue.  What 
seems  to  be  a  post  penetrating  the  osseous  tissue  is  a  bar  for  a  Gilmore 
attachment,  for  a  partial  plate,  resting  on  the  gum  tissue. 


Fig.    419A.       Radiographs    of    an    extracted    crowned    tooth,    made    by    directing    the    X-rays 
through  the  tooth  from  different  angles.      (By  R.  Ottolengui.) 


Figure  419A  shows  three  radiographs  of  an  extracted,  crowned 
upper  cuspid,  with  the  post  of  the  crown  passing  through  a  perforation 
on  the  labial.  The  radiographs  were  made  at  different  angles.  Number 
one  seems  to  show  the  post  following  the  canal;  number  two  seems  to 
show  the  post  passing  through  the  distal  side  of  the  root,  while  number 
three  shows  the  post  passing  through  the  labial  side  of  the  root. 

Number  one  was  made  by  directing  the  X-rays  straight  through  the 
tooth  from  labial  to  lingual  (X-rays  No.  2,  Fig.  419B).  Number  three 
was  made  straight  through  from  mesial  to  distal  and  number  two  was 
made  with  the  rays  passing  through  the  tooth  in  a  disto-lingual  direction 
(Fig.  419B,  X-rays  No.  3), 


376 


APPENDIX 


Figure  419C  is  a  case  from  practice.  Both  centrals  are  perforated. 
The  two  radiographs  show  these  perforations  and  fail  to  show  them  as 
the  angle  of  the  X-rays  is  changed.  A  careful  study  of  both  radiographs, 
using  a  rough  study  sketch  similar  to  Fig.  419B,  enabled  the  writer  to 
state  definitely  that  one  post  passed  through  the  labial  wall  of  the  root 
while  the  other  passed  through  the  other  tooth  to  the  lingual.  Examina- 
tion after  extraction  verified  the  diagnosis. 

18.  To  Assume  That  a  Broach  or  Wire  is  Following  a  Canal 
Because  it  Cannot  be  Seen  Extending  Too  Far  to  the  Mesial  or 
Distal. 


ARROW^a 


^— POINT  TO 
FACIAL  or 
ROOT 
CANAL 

--POINT  TO 
LINGUAL  OF" 
ROOT 


PLANE 


FIG.  419  B. 

Fig.  419B.  Diagrammatic  cross  section  of  a  tooth  root  showing  how  the  angle  at  which  the 
X-Rays  pass  through  the  tooth  may  cast  a  shadow  of  a  post  passing  tiirough  a  perforation  to  the 
facial  or  lingual  so  it  will  have  the  radiographic  appearance  of  passing  to  the  mesial  or  distal 
or  following  the  canal.  With  the  rays  passing  through  the  tooth  as  indicated  by  "  X-rays  No.  1," 
a  post  passing  far  enough  through  the  root  to  the  facial  will  have  the  radiographic  appearance 
of  passing  to  the  mesial  while,  if  the  post  passes  through  the  root  on  the  lingual  far  enough,  it 
will  have  the  radiographic  appearance  of  passing  through  the  side  of  the  root  to   the   distal. 

Direct  the  rays  through  the  tooth  as  per  arrow  No.  3  and  the  reverse  is  true,  i.  e.,  a  facial 
perforation  has  the  radiographic  appearance  of  being  on  the  distal,  while  a  lingual  perforation 
has  the  appearance  of  being  on  the  mesial. 

With  the  rays  passing  through  the  tooth  as  per  arrow  No.  2.  a  post  passing  to  the  facial  or 
Ungual  will  have  the  radiographic  appearance  of  following  the  canal. 


Fig.   419C.      Two  central  incisors  in  the  same  mouth.     The  posts  in  the  two  centrals  pass  through 

perforations,   one  to  the  labial,  one  to  the  lingual.      The  two   radiographs   respectively  both   show 

and  fail  to  show  the  posts  passing  through  the  perforationa. 


READING    RADIOGRAPHS 


Z77 


Figure  420  shows  a  wire  apparently  following  the  canal  in  a  lower 
bicuspid.  Figure  421  is  of  the  same  tooth  and  wire,  but  made  at  a  dif- 
ferent angle ;  the  wire  seems  to  be  too  far  distally.  In  reality  it  is  too 
far  buccally.  iStudy  Figure  422. 

19.  To  Mistake  a  Canal  Filling  Passing  Into  a  Crooked  Root 
For  a  Canal  Filling  Material  Passing  Through  a  Perforation 
Through  the  Side  of  the  Root. 

Figure  423  shows  canal  filling  material  passing  into  a  crooked  buccal 
root  of  an  upper  first  bicuspid.    The  outline  of  the  buccal  root  cannot  be 


Fig.   420.      Wire  apparently   following   canal  in 
lower  bicuspid. 


CANAL 


Fis.  421.  Same  case  as  Fip.  420  made  at  dif- 
ferent angle.  Wire  seems  to  pass  to  distal, 
but  in  reality  passes  too  far  to  the  buccal. 
(See  Fig.  422.) 


POINT  TO  BUCCAL 
'   OF  CANAL 


Fig.   422.      Di.^gram  explanatory  of  Fig.   421. 

seen  clearly  and  the  case  was  diagnosed  a  perforation  through  the  side  of 
the  root  with  the  canal  filling  passing  through  it. 

20.  To  State  Definitely,  From  the  Appearance  of  Flat  Radio- 
graphs (Not  Stereoscopic  Radiographs)  That  Impacted  Teeth  Lie 
to  the  Lingual  or  Facial  of  the  Other  Teeth. 

It  is  practically  always  impossible  to  determine,  from  a  single  flat 
negative,  the  facio-lingual  location  of  an  impacted  tooth.  The  radio- 
dontist  should  make  stereoscopic  radiographs  or  he  should  refrain  from 


378  APPENDIX 

making  himself  absurd  by  making  definite  statements  regarding  some- 
thing of  which  he  has  no  definite  knowledge. 

21.  To  Mistake  a  Small  Cervical  Filling  For  a  Pulp  Stone. 
See  Fig.  178  and  the  description  of  it. 

22.  To  Assume  That  a  Filling  in   the  Crown  of  a  Tooth 
Enters  the  Pulp  Chamber  When  it  Does  Not. 


Fig.   423.      The  canal  filling  in  the  crooked  buccal  root  of  the  first  bicuspid  was  thought  to  be 

canal  filling  material  passing  through  the  side  of  the  root;  the  outline  of  the  buccal  root  is  not 

distinct  and  so  was  not  seen  by  the  diagnostician. 

Unless  the  filling  enters  the  pulp  chamber  as  in  Fig.  444  or  unless 
the  cavity  is  a  simple  occlusal  one  without  buccal  or  lingual  extensions 
it  is  usually  impossible  to  determine  whether  a  filling  in  the  crown  of  a 
tooth  encroaches  on  the  pulp  or  not.  Proximo-occlusal  filHngs  and  fillings 
on  the  buccal  and  lingual  surfaces  often  have  the  appearance  of  en- 
croaching on  the  pulp  when  their  shadow  only  overlaps  the  pulp  in  the 
radiograph.  When  it  is  suspected  that  a  filling  encroaches  on  the  pulp, 
an  ocular  study  of  the  tooth  and  filling  should  be  made.  This  was  done 
in  the  case  of  Fig.  444,  for  example,  and  the  outline  of  the  cavity  in  the 
tooth  was  such  as  to  fail  to  explain  at  all  the  projection  which  seems  to 
enter  the  pulp  chamber.  Hence,  it  was  assumed  that  the  filling  did 
extend  into  the  pulp  chamber,  and  this  diagnosis  was  accordingly  made. 
Had  there  been  an  extension  of  the  filling  onto  the  buccal  or  lingual  of 
the  shape  of  the  material,  which,  in  this  case,  passes  into  the  pulp 
chamber,  this  extension  would  have  been  held  responsible  for  the  ap- 
pearance of  filling  material  passing  into  the  pulp  chamber. 

23.  To  Assume,  From  the  Appearance  of  Flat  Radiographs 
(Not  Stereoscopic  Radiographs)  That  the  Root  of  an  Upper  Pos- 
terior Tooth  Penetrates  the  Antrum. 

It  is  impossible  to  determine  from  the  appearance  of  a  flat  radio- 
graph whether  the  root  of  a  tooth  penetrates  the  antrum  or  not.    The  ap- 


READING    RADIOGRAPHS 


379 


pearance  of  the  radiograph  would  be  the  same  if  the  root  passed  to  the 
buccal  or  Ungual  of  the  antrum  as  it  would  if  it  entered  it.  In  radio- 
graphs made  on  films  held  in  the  mouth  the  roots  of  teeth  may  seem  to 
enter  or  lap  the  antrum  when  they  do  neither.     (Fig.  397.) 


Fig.  424.  Dark  area  in  apical  region 
of  upper  cuspid.  This  tooth  is  not 
abscessed;  the  bone  change  is  due  to 
abscess  of  the  lateral  incisor. 


Fig.    425.      Note    that    a    radiograph    would    give    no 

record  of  the  labio-lingual  depth  of  the  abscess 

cavity.      (Courtesy  Ash's  Monthly.) 


24.  To  Fail  to  Take  Into  Account  That  an  Abscess  Cavity 
May  Lap  to  the  Lingual  or  Facial  of  the  Adjoining  Teeth,  Giving 
THE  Radiographic  Appearance  of  Their  Involvement  but  Without 
Involving  Them. 

In  Fig.  424  an  abscess  at  the  apex  of  the  lateral  incisor  seems  to  in- 
volve the  cuspid,  but  this  is  due  to  lapping  of  the  abscess  cavity  to  the 
lingual.  The  cuspid  is  a  vital  tooth.  It  is  of  normal  color  and  responds 
normally  to  the  electric  test  for  pulp  vitality. 

25.  To  Fail  to  Consider  the  Element  of  Depth  When  Judging 
the  Size  of  an  Abscess  Cavity. 

Figure  425  is  made  from  a  photograph  of  a  skull.  Note  the  labio- 
lingual  depth  of  the  abscess  cavity  and  how  a  radiograph  would  fail  to 
indicate  the  true  size  of  the  cavity.  This  limitation  of  the  radiograph 
must  be  constantly  borne  in  mind. 

26.  To  Mistake  Normal  Resorption  of  Bone,  Due  to  Age,  For 
Pyorrhea  Alveolaris. 

The  fact  is  well  established  that  the  sharp  point  of  bone  seen  in  radio- 
graphs between  teeth  is  lost  as  age  advances.  This  change,  due  to  age, 
should  not  be  confused  with  pyorrhea  alveolaris. 

27.  To  Fail  to  Take  Into  Account  the  Effect  the  Tipping  of 
a  Tooth  to  the  Lingual  or  Facial  Will  Have  on  the  Appearance 
OF  the  Tooth  in  the  Radiograph. 


38o 


APPENDIX 


Figure  426  shows  a  lower  molar  which  seems  to  have  very  short 
roots.  When  extracted  the  roots  of  this  tooth  were  found  to  be  of  normal 
length.  Figure  427  illustrates  why  the  roots  of  the  molar  in  Fig.  426 
appeared  short — "  the  tooth  was  tipped  lingually."* 


Fig.  426.  The  roots  of  the  lower  first 
molar  seem  very  short,  but,  upon 
extraction,  they  were  found  to  be 
of  normal  length. 


XRAY5 


XRAYS 


Fig.  427.     Diagram  explana- 
tory of  Fig.  426. 


To  obtain  a  true  radiographic  shadow  of  a  tooth  like  the  molar  il- 
lustrated in  Fig.  426  and  diagramed  in  Fig.  427,  it  is  necessary  to  direct 
the  X-rays  lingually  and  downward  so  as  to  pass  through  the  tooth  at 
right  angles  to  its  long  axis. 

28.  To  State  Definitely  That  a  Rarefied  Area  at  the  Apex 
OF  A  Root  Represents  Infection,  Without  Considering  the  Anat- 
omy of  the  Parts  and  the  Symptoms  and  History  of  the  Case. 

It  is  very  common  practice  for  those  unskilled  in  the  interpretation 
of  radiographs  to  consider  nothing  at  all  except  the  lights  and  shadows  in 
the  radiograph  and  to  blandly  call  any  rarefied  area  at  the  apex  of  a 
tooth  "  an  abscess." 

That  things  other  than  infection  arising  from  the  tooth  may  cause  a 
rarefied  spot  at  its.  apex  has  been  pointed  out  elsewhere — See  Figs.  393, 
394,  395»  396,  399,  40i,  403  and  others. 

When  a  rarefied  area  occurs  at  the  apex  of  a  root  with  an  imperfect 
canal  filling,  the  imperfection  of  the  canal  filling  causes  us,  almost  re- 
gardless of  any  other  consideration,  always  to  look  upon  the  rarefied  area 
as  one  which  very  probably  indicates  infection. 

Do  abscess  cavities,  which  have  been  freed  from  infection,  fill  with 
new  bone  or  do  they  fill  with  fibrous  tissue  ?  The  question  was  discussed 
extensively  a  couple  of  years  ago.  Much  evidence  has  been  brought  forth 
in  the  form  of  post-operative  radiographs  to  prove  that  there  is  a  recon- 


*  Dr.  Ottolengui. 


READING    RADIOGRAPHS  381 

struction  of  bone  in  abscess  cavities.  The  fact  is  established  :  bone  will  fill 
abscess  cavities  after  proper  treatment.  But  this  proves  only  that  we  do 
get  bone  reconstruction  in  some  cases;  it  does  not  prove  that  abscess  cavi- 
ties do  not  fill  with  fibrous  tissue.  Perhaps  they  do ;  perhaps  they  do  not ; 
the  question  is  not  settled. 

An  abscess  cavity  filled  with  uninfected  fibrous  tissue  would  have 
practically  the  same  radiographic  appearance  as  one  filled  with  infectious 
material. 

Since  there  is  no  doubt  at  all  about  the  possibility  of  getting  bone 
reconstruction  in  abscess  cavities,  and  there  is  some  doubt  as  to  whether 
such  cavities  ever  become  filled  with  uninfected  fibrous,  cartilasre-like 
tissue  (it  has  not  been  conclusively  proved  that  they  ever  do)  we  must 
consider  it  at  least  a  had  sign  when  we  fail  to  get  bone  reconstruction; 
then  take  into  account  the  local  and  general  symptoms  and  be  governed 
accordingly  in  our  conclusions.     (See  Appendix,  Chapter  XI.) 

Knowledge  of  what  treatment,  if  any,  has  been  given  will  assist  in 
determining  whether  or  not  a  shadow  at  the  apex  of  a  tooth  represents 
infection.  As  the  size  of  the  originally  infected  area  increases  the  method 
indicated  for  overcoming  the  infection  changes.  A  small  area  of  infec- 
tion can  be  overcome  by  forcing  some  disinfectant,  such  as  phenolsul- 
phonic  acid  or  a  three  per  cent,  solution  of  tincture  of  iodine  in  water 
through  the  tooth  into  the  infected  area ;  a  larger  area  can  be  disinfected 
by  the  ionization  method ;  a  still  larger  area  may  necessitate  curettement 
and  root  resection ;  while  extensive  infection  may  necessitate  extraction. 
Thus  if  a  shadow  persists  at  the  apex  of  a  tooth  after  treatment  with 
phenolsulphonic  acid,  when  the  original  infection  was  such  as  to  indicate 
extraction  or  at  least  curettement,  the  shadow  may  be  said  to  represent 
infection.  After  a  case  has  been  treated,  when  in  doubt  as  to  whether  or 
not  a  shadow  indicates  infection  it  is  well  to  ray  the  part  repeatedly  at 
intervals  of  two  or  three  months.  If  the  shadow  gets  larger,  a  diagnosis 
of  infection  may  be  made;  if  it  gets  smaller  we  may  assume  infection  has 
been  overcome  for  the  time  being,  at  least ;  if  it  remains  the  same  it  is 
very  probable  that  infection  has  not  been  overcome,  though,  in  the  light 
of  our  present  knowledge  of  the  subject,  the  radiograph  proves  nothing 
conclusively  one  way  or  the  other  in  this  latter  event.  Noticeable  bone 
reconstruction  takes  place  usually  within  three  months  and  large  cavities 
are  filled  in  about  six  months  to  a  year. 

When  making  a  series  of  radiographs  of  the  same  case,  great  care 
should  be  taken  to  have  the  poses  for  the  different  radiographs  as  near 
the  same  as  possible  as  change  in  viewpoint  of  observation  of  the  part 
may  change  appearances  greatly. 


382  APPENDIX 

29.  To  State  That  No  Infection  Exists  Because  No  Abscess 
Cavity  Can  Be  Observed. 

Infection  in  the  end  of  an  unfilled  canal  and  in  the  periapical  space 
may  exist  without  destruction  of  bone.  Just  because  there  is  not  a  suf- 
ficient amount  of  the  right  kind  of  infection  to  produce  bone  destruction 


Fig.   42S.      Bone  destruction  and  osteosclerosis  at  apex  of  upper  first  bicuspid. 

does  not  mean  that  there  is  no  infection  at  all.  If  the  symptoms,  local 
or  general,  indicate  infection,  unfilled  canals  should  be  looked  upon  with 
great  suspicion,  even  if  the  bone  is  not  destroyed.  In  such  cases  dense 
areas  in  the  bone  and  hypercementosis  may  be  taken  as  contributing  evi- 
dence of  infection. 

A  small  abscess  cavity  just  beyond  the  end  of  the  root  will  always 
show  in  a  well-made  radiograph,  but  a  small  abscess  cavity  at  the  apex, 
on  the  facial  or  lingual  side  of  the  root,  may  fail  to  show.  Visualize  a 
small  abscess  on  the  buccal,  at  the  apex,  but  not  extending  above  it,  in 
Fig.  414.  It  would  fail  to  register — unless  it  were  considerably  wider 
than  the  root  of  the  tooth  mesio-distally — with  the  rays  passing  through 
the  tooth  as  per  arrow  "  X-rays  No.  3,"  Fig.  412.  With  the  rays  passing 
through  the  tooth  as  per  "  X-rays  Nos.  i  and  2,"  Fig.  412,  it  would  very 
likely  show  in  the  negative.  Hence,  as  I  have  pointed  out  elsewhere,  the 
necessity  of  radiographing  the  same  field  at  different  angles.  A  single 
radiograph  of  a  part  does  not,  by  any  means,  always  represent  a  good 
radiographic  examination  of  the  part. 

30.     To  Fail  to  Bear  in  Mind  That  Osteodensity  as  Well  as 

OSTEOPOROSITY    MaY    BE    CaUSED    BY    INFECTION. 

As  I  have  already  stated  (See  under  Mistakes  7  and  29)  some  osteo- 
density as  well  as  osteoporosity  may  be  caused  by  infection.  This 
knowledge  will  often  assist  in  rendering  a  correct  judgment  regarding 
radiographic  findings. 

Figure  428  shows  both  destruction  and  eburnation  or  sclerosis  of 
bone.    The  bone  destruction  is  just  at  the  apex  of  the  first  bicuspid.     Im- 


READING    RADIOGRAPHS 


383 


mediately  surrounding  the  area  of  bone  destruction  is  a  rim.of  dense  bone. 
(In  this  case  the  permanent  cuspid  is  missing,  the  temporary  cuspid  is 
shell  crowned  and  about  all  of  the  root  is  resorbed.) 

Figure  429  is  a  case  in  which  we  see  an  imperfect  canal  filling,  and 
evidence  of  osteoblastic  stimulation — which  is  probably  infective  in  nature 
— at  the  apex  of  the  second  bicuspid.  In  this  case  it  seems  that  we  have 
practically  no  bone  decalcification.  While  the  canal  filling  in  this  case 
reaches  the  end  of  the  root,  I  consider  it  imperfect  because,  judging  from 
the  buckled,  bent  condition  of  the  gutta  percha  point,  the  canal  filling  does 
not  fill  the  canal  solidly  full. 


Fig.  429.     Osteosclerosis  apex  upper  second 
bicuspid. 


Fig.   430.      Bone   destruction,   bone   eburnation 

and  hypercementosis   distal   root, 

lower  first  molar. 


Figure  430  shows  (i)  bone  destruction,  (2)  osteosclerosis,  (3) 
hypercementosis  in  the  region  of  the  apex  of  the  distal  root  of  the  lower 
first  molar. 

31.  To  Assume,  When  Observing  an  Abscess  Cavity  at  the 
Apex  of  a  Tooth  With  a  Well-Filled  Canal,  That  the  Abscess  Oc- 
curred After  Canal  Filling. 

It  is  such  faulty  reasoning  that  I  may  say  it  is  lack  of  reasoning 
to  point  to  a  well-filled  canal  at  the  end  of  which  is  a  large  abscess  cavity, 
and  say,  "This  canal  filling  has  failed.  It  is  useless  to  fill, canals  as  this 
one  is  filled."  Of  course,  the  abscess  cavity  may  have  existed  for  years 
before  the  canal  filling  was  placed  in  the  tooth,  but  the  universal  tendency 
is  to  assume  that  it  did  not,  but  that  it  developed  after  the  canal  filling 
was  inserted. 

It  should  also  be  remembered  that  there  is  something  more  to  the 
treatment  of  pulp  canals  than  the  mere  mechanical  filling.  No  difference 
how  mechanically  perfect  a  canal  filling  may  be  it  will  fail  unless  the 
proper  aseptic  and  antiseptic  measures  have  been  taken.  Mechanical  per- 
fection of  the  canal  filling  is  only  one  factor  which  contributes  to  the 
successful  treatment  of  teeth;  and,  important  as  it  is,  it  is  not,  in  my 


.384  APPENDIX 

present  opinion,  as  important  as  asepsis,  antisepis  and  disinfection.  A 
canal  filling  which  simply  reaches  the  end  of  the  root  but  does  not  fill  the 
canal  full  is,  of  course,  not  a  good  one,  though  it  is  often  accepted  as 
such. 

32.     To  Expect  to  See  a  Fistulous  Tract. 

It  is  a  human  characteristic  to  see  the  things  we  are  looking  for  and 
rather  expect  to  see,  or  want  to  see.  Hence,  the  many  misinterpretations 
of  radiographs.  It  is  very  seldom  possible  to  observe  a  fistulous  tract 
unless  it  is  injected  with  some  agent  such  as  bismuth  paste. 

TfT).  To  Give  Positive  Diagnosis  of  Pulp  Stones  From  the  Ap- 
pearance OF  One  Radiograph. 

Even  when  the  finding  can  be  observed  quite  clearly  the  writer  usu- 
ally deems  it  expedient  to  re-ray  the  part  before  giving  a  diagnosis  of 
pulp  stones. 

34.  To  Try  to  Make  One  Radiograph  Do  the  Work  of  Two, 
OR  Several. 

It  is  not  an  uncommon  mistake  to  try  to  make  one  small  film  nega- 
tive take  in,  say,  for  example,  the  central  incisor,  the  lateral  incisor,  the 
cuspid  and  the  first  bicuspid.  While  all  of  these  teeth  might  be  radio- 
graphed on  one  negative,  some  or  all  of  them  would  be  distorted.  It 
would  be  better  to  make  two  negatives. 

It  is  a  mistake  to  radiograph  one  side  of  the  jaw  looking  for,  say, 
an  unerupted  bicuspid,  and  assume  that  the  presence  or  absence  of  the  un- 
erupted  tooth  as  revealed  in  the  one  radiograph,  is  sufficient  to  indicate 
the  same  condition  in  the  other  side  of  the  jaw.     (Fig.  302.) 

One  radiograph  of  a  part  is  simply  one  view  of  the  part  from  one 
viewpoint.  No  one  thing  contributes  more  to  mistakes  in  diagnosis  than 
pinning  one's  faith  implicitly  upon  the  appearance  of  a  single  radiograph. 
The  more  radiographic  work  I  do  the  more  I  find  myself  radiographing 
the  same  part  again  and  again  before  venturing  an  opinion. 

35.  To  Mistake  Hypercementosis  For  a  Poorly  Made  Radio- 
graph. 

In  some  cases  of  hypercementosis  it  is  impossible  to  show  the  outline 
of  the  root  of  the  tooth  distinctly.     (Fig.  431.) 

36.  Not  to  Know  the  Difference  Between  a  Good  Radiograph 
AND  A  Poor  One. 

Figure  432  shows  a  wire  apparently  in  the  canal  of  an  upper  lateral. 
Figure  432,  however,  is  a  distorted  radiograph  due  to  the  angle  of  the 
X-rays  and  bending  of  the  film.  Figure  433  is  of  the  same  tooth,  is  a 
good  radiograph,  and  shows  the  wire  passing  through  a  perforation  to  the 
distal. 


READING    RADIOGRAPHS  385 

Figure  434  shows  the  outline  of  the  roots  of  a  lower,  first  molar 
very  indistinct.     Figure  435  is  of  the  same  tooth  but  this  time  the  rays 


Fig.    4ol.      Hypercementosis    of   upper   bicuspids.      The   outline    of   the    roots    of   the   bicuspids 
not  distinct,  due  to  the  hypercementosis,  not  to  some  fault  in  technic. 


Fig.  433.     Same  as  Fi^.  432.     Radiograph  not 
Fig.   432.      Wire  apparently  following  canal  in  distorted.      See   wire  passing  through 

upper  lateral   root.      Distorted   radiograph.  side  of  root  to  the  distal. 


have  been  directed  through  the  tooth  at  a  different  angle  (arrow  No.  3, 
Fig.  436)  and  the  outline  of  the  roots  is  comparatively  distinct. 

When  the  X-rays  pass  through  the  tooth  as  indi- 
Tlg.  436.  cated  by  arrows  i  and  2,  Fig.  436,  the  outline  of  the 

roots  will  be  more  or  less  indistinct ;  when  the  rays 
pass  straight  through  the  tooth,  as  indicated  by  arrow  No.  3,  Fig.  436, 
the  outline  of  the  roots  in  the  radiograph  will  be  distinct  unless  there  is 
hypercementosis,  osteodensity,  or  tipping  of  the  tooth  to  the  buccal  or 
ling-ual. 


386 


APPENDIX 


Fig.  434.  Outline  of  roots  of  lower  first  molar 
indistinct.  (Rays  passed  through  tooth  as 
per  arrow  No.  1,  or  No.  2,  Fiu.  4.30.) 


Fig.  4.35.  Outline  of  roots  of  lower  first  mo- 
lar more  distinct  than  in  Fig.  434.  (Rays 
passed  through  tooth  as  per  arrow  No.  3, 
Fig.  430.) 


LOWER  MOLAR 


4 


ARR0W*3 


MESIAL 


Fig.   436.      Diagrammatic  cross  section  of  a  lower  first  molar  through  the  pulp  chamber. 


Fig.    436A.      Wires   in   lower   first  molar.      X-        Fig.    436B.      Same   case    as    Fig.    43GA,   made 
rays  passed  through  tooth  diagonally;  arrows  with    X-rays   passing   through    tooth    as    indi- 

No.  1  and  No.  2,  Fig.  436.  cated  by  arrow  No.  3,  Fig.  436.     The  wires 

in     the     mesial     canals     are     superimposed 
throughout  most  of  their  length.. 


READING    RADIOGRAPHS 


387 


With  the  rays  passing  through  the  tooth  as  per  arrow  No.  i,  the 
shadow  of  the  mesio-buccal  canal  will  be  thrown  to  the  mesial  of  the 
mesio-lingual  canal  (see  Fig.  436A),  with  the  rays  passing  through  the 
tooth  as  per  arrow  No.  2,  the  mesio-buccal  canal  will  be  thrown  to  the 
distal  of  the  mesio-Hngual  canal  and  the  appearance  of  the  radiograph 
will  be  similar  to  Fig.  436A ;  with  the  rays  passing  through  the  tooth  as 
per  arrow  No.  3  of  the  two  mesial  canals  will  be  superimposed,  one  over 
the  other — Fig.  436B. 


m 
o 


Fig.   43GC.      Cross  section  of  mesial  root  of  lower  molar.      See  text. 

In  this  connection  it  may  prove  profitable  for  the 
Tig.  4360.  reader  to  study  Fig.  436C,  which  diagrams  a  cross 

section  of  the  mesial  root  of  a  lower  molar  with  the 
X-rays  passing  through  it  as  indicated  by  arrows  one  and  two  in  Fig. 
436.  Note  that  the  shadow  cast  on  the  film  between  lines  B  and  C  would 
be  denser  than  between  the  lines  A-B  or  C-D.  Thus  on  the  radiograph  the 
outline  of  the  root  would  be  either  not  well'  defined  (Fig.  434)  or  the  root 
would  have  the  appearance  of  having  a  necrotic  surface  (Fig.  205  is  a 
fine  example). 

Figure  436D  shows  two  radiographs  of  a  lower 
Tig.  436D.  first    molar.      The    radiograph    made    on    the    small 

film  shows  two  very  short  canal  fillings  in  the  mesial 
root,  one  of  which  seems  to  pass  through  the  side  of  the  root  to  the 
mesial.  In  the  large  radiograph,  made  on  a  plate,  the  two  canal  fillings 
in  the  two  mesial  roots  are  superimposed  one  on  the  other,  and  they  do 
not  have  the  appearance  of  passing  through  the  mesial  side  of  the  root. 
The  canal  filling  in  the  small  film  radiograph  seems  to  pass  through  the 
side  of  the  root  because  where  the  filling  ends  the  shadow  of  the  root  out- 
line is  faint  as  between  lines  A-B  and  C-D,  Fig.  436C. 


388 


APPENDIX 


Fig.    436D.      Two  radiographs  of  the  same  lower  first  molar.      In    one   the   canal  filling   seems   to 
pass  through  the  side  of  the  root;  in  the  other  it  seems  to  follow  the  canal. 

Figure   437   shows    what   seems   to   be   a   tumorous 
TiflS.  437  and  43$.       growth  in  the  upper  molar  region.    It  is  not  a  tumor  ; 
it  is  the  malar  process  thrown  in  the  position  it  oc- 
cupies because  the  X-rays  were  directed  through  the  parts  from  a  posi- 


Fig.    437.      Malar   process   having 
appearance   of   tumor. 


Fig.    43S.      Same   as   Fig.   437,   made 
at   different   angle. 


tion  which  was  too  high.     Figure  438  is  of  the  same  case,  made  with  the 
X-rays  properly  directed  through  the  parts. 


READING    RADIOGRAPHS 


389 


Fig.    439.      "  Horrible    Example."      A    number    of    radiographs    intended    to    be    a    radiographic 
examination  of  all  the  teeth   in   the  mouth.      In   reality   it  is  a  radiographic   examination   of  only 

a    very   few   teeth. 

2,7.  To  Make  Just  One  Radiograph  of  a  Part  and  Stop, 
Calling  It  a  Radiographic  Examination. 

The  inexpedience  of  depending  too  implicitly  on  the  appearance  of 
one  radiograph  has  already  been  demonstrated  in  this  chapter. 


390 


APPENDIX 


Figure  439  shows  the  result  of  applying  the  principle  of  making  just 
one  exposure  of  a  part  and  calling  that  a  radiographic  examination  of 
the  part.  Figure  439  is  intended  to  be  a  radiographic  examination  of  all 
of  the  teeth,  but  most  of  the  radiographs  are  so  poor  that  it  is  really  a 
radiographic  examination  of  only  a  very  small  number  of  teeth. 

I  cannot  impress  this  point  too  strongly,  the  making  of  a  radiograph 
is  equivalent  to  having  a  look  at  the  part  from  one  viewpoint.  It  is  often 
necessary,  if  we  wish  to  make  a  thorough  radiographic  examination,  to 
view  the  part  from  different  viewpoints.     It  is  very  often,  in  fact,  usually 


© 


0 


.LINGUAL 
FILM     ^.^'-'DI5T0-BUCCAL 

B 
C 

•ME510-BUCCAL 


FILM 


Fig.   440.      Cross  section  upper 
first   molar. 


Fig.   441.      Angle  of  X-rays, 
arrow  B,   Fig.  440. 


Fig.  442.      Angle  of  X-rays, 
arrow  A,   Fig.   440. 


Fig.   443.      Angle  of  X-rays, 
arrow  C,  Fig.  440. 


necessary  to  make  more  than  one  radiograph  to  view  the  upper  molar 

roots  satisfactorily.     Study  Fig.  440. 

Directing  the   rays   through   the   part   indicated   by 

TiflS.  440,  441,  442       arrow  B  will  usually  throw  the  mesio-buccal  root 
ana  443*  ...         ,  ./.,,., 

a  little  to  the  mesial  of  the  lingual  root  as  seen  in 

Fig.  441  . 

Directing  the  rays  through  the  part  as  indicated  by  arrow  A,  will 

throw  the  mesio-buccal  root  farther  to  the  mesial  of  the  lingual  root. 

(Fig.  442.) 


READING   RADIOGRAPHS 


391 


Directing  the  rays  through  the  part  as  indicated  by  Arrow  C,  will 
throw  the  disto-buccal  root  to  the  distal  of  the  lingual  root.  (Fig.  443.) 

Quite  often,  when  the  disto-buccal  root  is  thrown  to  the  distal  of  the 
lingual  root,  the  end  of  the  disto-buccal  root  still  cannot  be  seen — it  seems 
to  be  absorbed.  (See  Fig.  429,  The  First  Molar.)  This  appearance  is 
due  to  the  fact  that  the  root  is  so  small  that  it  does  not  throw  a  shadow 
of  sufficient  density  to  be  seen  clearly.  This  must  be  kept  in  mind  or  the 
radiodontist   will   mistake  normal   conditions    for   disease   in   the   apical 


Fig.  444.      Unerupted,  malposed,  lower  cuspid.     Age  of  patient  about  40. 


region  of  the  disto-buccal  roots.  There  is  also  sometimes  a  normal 
porosity  of  bone  in  the  apical  region  of  the  mesio-buccal  root  which  may 
be  mistaken  to  indicate  disease  if  the  operator  does  not  know  that  such  a 
condition  may  be  normal.  To  differentiate,  apply  the  electric  test  to  the 
tooth  to  determine  pulp  vitality,  look  for  osteosclerosis  and  take  into  ac- 
count the  degree  of  darkness  in  the  suspicious  area. 

The  roots  of  the  second  and  third  upper  molars  are  often  so  close 
together,  and  the  malar  process  is  so  likely  to  cast  a  shadow  over  them, 
that  it  is  not  infrequently  impossible  to  distinguish  the  different  roots. 


392 


APPENDIX 


38.  To  Depend  on  Intra-Oral  Radiographs  Alone,  Especially 
IN  Cases  of  Neuralgia,  Facial  Fistula,  Impacted  Third  Molars  and 
Abscess  of  the  Lower  Bicuspids. 

Case :  Facial  fistula.  A  radiograph,  made  on  a  small  film,  showed 
very  small  spots  indicating  a  slight  infection  at  the  apices  of  the  roots  of 
a  lower  second  molar.  Continued  treatment  of  the  tooth  did  not  benefit 
the  case.  It  was  decided  that  the  molar  should  be  extracted,  but  before 
doing  this  another  radiograph  was  made ;  this  time  on  a  large  plate.  The 
second  radiograph,  made  on  the  plate,  revealed  the  presence  of  an  ab- 
scess at  the  apex  of  the  lower  first  bscuspid,  which  tooth  had  no  carious 
cavity  in  it.  This  'tooth,  the  lower,  first  bicuspid,  was  opened  and  treated 
and  the  case  recovered  promptly.  The  large  plate  should  have  been  made 
in  the  first  place,  which  would  have  enabled  the  operator  to  get  at  the  seat 
of  the  infection  without  delay. 


Fig.   445.      Unerupted,   malposed,   upper   and   lower   third   molars. 

Figure  444  is  the  radiograph  made  of  a  case  of  neuralgia  of  many 
years  standing.     The  shadow  in  the  anterior  region  of  Fig.  444  is  an  un- 


READING    RADIOGRAPHS  393 

erupted  lower  cuspid.  Note  also  the  very  small  abscess  of  the  lower 
third  molar.  The  abscess  is  no  larger  than  an  unusually  large  periapical 
space,  but  observe  the  filling  in  the  crown  of  the  tooth  enters  the  pulp 
chamber  and  there  is  no  canal  filling  in  the  canals.  Had  a  small  film  been 
used  and  the  condition  of  the  lower  third  molar  disclosed  it  is  highly  im- 
probable that  the  examination  would  have  been  carried  further  and  so  the 
real  cause  of  the  trouble  would  not  have  been  located.  I  say  the  real 
cause  of  the  trouble  would  not  have  been  located,  because  removal  of  the 
malposed  tooth,  without  treatment  of  the  third  molar,  effected  a  cure. 

When  making  radiographs  for  impacted  third  molars,  there  will  be 
less  distortion,  and  the  radiograph  is  more  likely  to  show  all,  instead  of 
just  a  part,  of  the  unerupted  tooth  and  the  surrounding  parts,  if  it  is  made 
on  a  plate. 

Figure  445  is  a  radiograph  of  a  case  of  neuralgia,  in  which  both  the 
dentist  and  the  patient  insisted  that  the  lower  third  molar  had  been 
extracted.  The  radiograph  was  made  in  a  search  for  an  upper  third 
molar.  It  shows  both  an  upper  and  a  lower  third  molar.  Of  course,  the 
lower  third  molar  would  not  have  been  discovered  had  the  radiograph 
been  made  on  a  small  film. 

The  advantage  of  the  large  extra-oral  radiograph  over  the  small 
intra-oral  one  for  radiographing  the  lower  bicuspids  is  given  in  the  dis- 
cussion of  mistake  No.  i. 

39.  To  Fail  to  Use  a  Reading  Glass  When  Studying  Nega- 
tives AND  So  Avail  One's  Self  of  the  Great  Assistance  Rendered 
BY  THE  Practice. 

The  advantage  in  using  a  reading-glass  to  study  dental  radiographs 
is  so  great,  and  the  inconvenience  of  obtaining  and  using  such  a  glass  so 
slight,  that  it  must  be  considered  a  mistake  not  to  avail  one's  self  of  this 
valuable  aid. 

40.  To  Fail  to  Use  the  Electric  Test  for  Vitality  of  Pulps  in 
Connection  with  Radiographic  Examination. 

*The  use  of  some  electric  machine  to  test  the  vitality  of  the  pulp, 
I  find  absolutely  indispensable  in  the  practice  of  radiodontia.  Likewise 
it  will  be  found  indispensable  to  the  general  practitioner  of  dentistry  once 
he  learns  to  use  it  and  depend  on  it.  The  technic  of  applying  this  test 
is  extremely  simple. 

Figure  446  is  a  small  machine,  of  the  writer's  design,  which  may  be 
used  to  test  teeth  to  determine  the  vitahty  of  their  pulps.  In  principle  of 
construction  it  is  a  Faradic  machine.  The  source  of  the  current  to  excite 
the  machine  is  the  ordinary  dry  cell,  such  as  can  be  obtained  anywhere 


*  The  electric  test  for  pulp  vitality  is  not  original  with  the  writer. 


394 


APPENDIX 


in  the  civilized  world.  By  means  of  a  little  step-up  transformer  or  coil 
the  current  of  high  amperage  and  low  voltage,,  from  the  dry  cell,  is  trans- 
formed into  a  current  of  comparatively  low  amperage  and  high  voltage 
or  pressure.  The  amount  of  output  current  delivered  by  the  machine  is 
controlled  by  a  rheostat,  or  a  metal  sheath,  which  slides  in  between  the 
primary  and  secondary  winding  of  the  coil.  With  the  sheath  in  the  cur- 
rent is  weakest.  This  control  is  such  that  the  output  current  can  be 
gradually  increased  from  practically  nothing  to  the  capacity  of  the 
machine. 

^   t  -   *  ^  II  •  *        Plug   cords,    to    which   the    "  hand  "    and    "  dental  " 

Cccbttic  for  u5iitd  &  > 

electric  Pulp  testing     electrodes  are  attached,  into  machine.      (There  are 

liificninc.  three  places  or  sockets  into  which  the  cords  may  be 

plugged,  marked  "  L,"  "  M  "  and  "  R,"  Fig.  446.    With  the  cords  plugged 


NTERRUPTER 


r^. 


EOSTAT 


\HAND 
LECTRODE 


DENTAL 
ELECTRODE 


Fig.    440.      Author's   machine   for   testing   teeth   for   vitality   of   the   pulp.      Size   8Y2    inches   long, 
4%  inches  wide,  7  inches  high.     To  date,  Dec.   6,  1917,  this  machine  has  not  been  per- 
fected to  conform  fully  with  the  writer's  ideal. 

into  "  L  "  and  "  M,"  as  in  Fig.  446,  the  output  current  is  weakest.  With 
the  cords  plugged  into  "  L  "  and  "  R  "  the  output  current  is  strongest. 
Figure  446  is,  at  this  time,  still  in  the  process  of  construction.  It  is  my 
aim  to  have  the  machine  constructed  so  that  the  operator  will,  except  in 
the  rarest  cases,  ahvays  plug  into  "  L  "  and  "  R  "  and  find,  with  this  at- 
tachment to  the  machine,  that  he  can  get  all  the  gradation  of  current 
strength  he  desires.) 


READING    RADIOGRAPHS  395 

Polarity :  It  makes  no  practical  difference  about  polarity ;  either 
electrode  may  be  attached  to  either  socket. 

The  dental  electrode  is  insulated  save  for  the  metal  point  at  the  end. 
Wrap  the  metal  point  with  cotton  and  moisten  the  cotton  with  water 
or  sodium  chlorid  solution. 

Have  the  patient  hold  the  hand  electrode. 

Turn  the  main  switch,  when  there  should  be  a  humming  noise.  If 
there  is  no  humming  noise,  adjust  the  interrupter  screw. 

Start  with  the  resistance  of  the  rheostat  in,  that  is,  with  the  current 
weak,  and  touch  the  tooth  to  be  tested  with  the  dental  electrode.  Advance 
the  rheostat  as  necessary  to  get  sensation.  The  sensation  will  occur  in 
the  tooth  only — not  in  the  hand — -providing  the  pulp  is  vital.  If  the  pulp 
is  not  vital  there  will  be  no  sensation  with  the  machine  operating  at  its 
capacity.  Use  enough  current  to  cause  the  patient  to  jump  or  flinch 
slightly  but  definitely. 

Take  care  not  to  touch  the  patient  with  the  dental  electrode  any- 
where except  on  the  tooth  to  be  tested,  as  the  sensation  would  be 
unpleasant. 

.»-   -i^^-.  .  Crowned  teeth  cannot  be  tested. 

Limitattons  ^     ,       .  ,    ,  ,    ^,,.  „  , 

and  Points  in  I  eeth    with    large    metal    hllmgs :      Sometime    teeth 

CccbniC«  with  large  metal  filhngs  in  them  do  not  respond  to 

the  electric  test  when  their  pulps  are  vital ;  because  the  stimulus  of  the 
metal  filling  has  caused  the  pulp  to  recede  so  far.  Sometimes,  but  less 
frequently,  teeth  with  large  metal  fillings  do  respond  to  the  electric  test 
when  their  pulps  are  not  vital,  because  the  current  is  conveyed  through 
the  tooth  from  the  place  where  the  dental  electrode  was  applied  into  the 
metal  filling,  through  it,  into  the  gum  tissue  or  pericemental  membrane  or 
approximating  tooth. 

Teeth  with  pulp  stones  and  teeth  where  the  pulp  has  receded,  due 
to  the  age  of  the  patient,  are  less  sensitive  to  the  electric  test. 

Teeth  with  abraded  surfaces  are  usually  quite  sensitive  when  the 
electrode  is  applied  to  the  exposed,  or  nearly  exposed,  dentin.  However, 
in  some  such  cases  the  pulp  has  receded,  when  the  teeth  are  less  sensitive 
to  the  test. 

In  spite  of  the  limitations  enumerated,  the  fact  remains  that  the 
electric  test  for  determining  the  vitality  of  the  dental  pulp  is  by  far  the 
best  we  have.  Coupled  with  the  use  of  radiographs  it  enables  us  to  deter- 
mine the  vitality  of  the  pulps  of  most  teeth. 

When  testing  a  tooth  with  a  proximo-occlusal  or  proximo-incisal 
filling,  or  any  filling  passing  beneath  the  gum  margin,  do  not  touch  the 
filling — touch  the  enamel  only.     When  testing  such  teeth,  two  or  more 


396  APPENDIX 

thicknesses  of  rubber  dam  may  sometimes  be  placed  between  the  filling 
and  the  tooth  approximating  the  filling.  If  kept  dry,  the  rubber  acts  as 
an  insulation,  keeping  the  current  from  passing  into  the  approximating 
tooth. 

A  tooth  with  a  simple  filHng,  which  does  not  come  in  contact  with 
the  gum  tissue  or  an  approximating  tooth,  may  be  tested  by  touching  the 
dental  electrode  to  the  filling.  When  this  is  done,  the  current  should  be 
weak. 

The  teeth  being  tested  should  be  kept  dry;  with  cotton  rolls,  if  neces- 
sary, otherwise  the  current  will  pass  into  the  gums,  pericemental  mem- 
brane and  approximating  teeth,  through  the  saliva. 

When  the  electric  test  is  suggested  most  patients 
EkCtropbObia.  will  offer  some  objection,  saying  they  "  can't  stand 

electricity."  You  will  gain  your  patients'  confidence 
and  co-operation  by  telling  them  that  you  can  control  perfectly  the  amount 
of  current  used.  Then  prove  this  to  them.  Close  the  main  switch,  which 
will  start  the  mechanical  interrupter  and  cause  a  humming  noise.  Throw 
in  all  the  resistance  of  the  rheostat,  or  have  the  metal  sheath  clear  in,  and 
say  to  the  patient :  "  Now  I  am  using  so  little  current  you  will  scarcely 
feel  it,  if  you  feel  it  at  all."  Touch  a  tooth ;  most  any  tooth  except  the 
lower  incisors.  (The  amount  of  current  necessary  to  produce  sensation 
varies  directly  according  to  the  size  of  the  tooth.  Thus,  the  patients  would 
be  less  likely  to  feel  a  weak  current  on  an  upper  central  or  cuspid  than 
they  would  on  the  smaller  teeth  just  mentioned.)  With  the  current  weak 
the  patients  will  not  feel  it  or  the  sensation  will  be  very  slight  and  not 
really  painful.  Now  instruct  the  patients  that  you  will  use  only  enough 
current  to  produce  a  momentary,  warm,  stinging  sensation  in  the  tooth, 
and  proceed  to  do  so.  As  soon  as  you  show  the  patients  that  you  can  con- 
trol your  machine,  the  dread  of  its  use  is  practically  gone.  A  good 
psychic  effect  will  be  gained  by  calling  the  patients'  attention  to  the  fact 
that  you  do  not  wish  them  to  try  to  endure  pain,  but  simply  to  let  you 
know  as  soon  as  pain  is  produced  so  you  may  stop  it  immediately. 

A  machine  of  the  nature  of  the  tester  under  con- 
Ciability  of  JlCCident.      sideration  has  an  advantage  over  any  switchboard 

attachment  or  any  machine  deriving  its  electricity 
from  some  powerful  supply  in  that,  in  case  of  accident  or  improper  use, 
no  serious  accident  can  occur,  because  the  source  of  electric  supply,  the 
dry  cell,  is  so  small.  One  dry  cell  cannot  produce  enough  electricity  to 
cause  a  serious  or  very  painful  accident.  This  should  appeal  to  anyone, 
but  particularly  to  men  whose  knowledge  of  electricity  is  limited. 


READING    RADIOGRAPHS 


397 


The  extreme  value  of  the  electric  test  for  pulp 
■^05^^447^  and  B        vitality  can  best  be  illustrated  by  recounting  its  use 

in  the  following  case:  The  end  of  the  root  of  an 
upper  lateral  was  resected  to  cure  an  abscess.  The  wound  made  at  the 
time  of  the  operation  did  not  heal  normally.  A  radiograph  was  made, 
Fig.  447A.  It  seems  to  show  that  the  central  is  involved  in  the  lateral's 
abscess  cavity.  The  central  was  tested  for  vitality  of  its  pulp.  It  re- 
sponded to  the  electric  test,  indicating  a  vital  pulp.  Another  radiograph 
was  made,  Fig.  447B.  This  second  radiograph,  made  at  a  different  angle, 
shows  no  involvement  of  the  central,  and  what  may  or  may  not  be  an 
involvement  of  the  cuspid.    The  shadow  passing  to  the  apex  of  the  cuspid 


Fig.    447 A.      The   central   incisor   seem- 
to   be   involved   in  the   abscess. 


Fig.    44 7B.      Compare   with   Fig.    447A 
of   the   same  case. 


Fig.   448.      An  abscess  which   seems  to 

involve    both    the    lower    first    bicuspid 

and    the    cuspid. 


Fig.   449.      A  very  small  abscess  of  an 
upper    bicuspid. 


does  not  show  clearly.  The  cuspid  was  tested  and  its  pulp  did  not  re- 
spond to  the  application  of  the  current.  It  was  opened  and  found  to 
contain  a  putrescent  pulp.  Neither  the  central  incisor,  at  first  suspected, 
or  the  cuspid,  finally  opened,  had  carious  cavities  in  their  crowns.     A 


398  APPENDIX 

satisfactory  diagnosis  in  this  case  would  have  been  impossible  without 
the  use  of  the  electric  tester,  as  well  as  the  X-rays. 

Another  case :     Figure  448.     From  the  appearance 

Tifl,  44$,  of  the  radiograph  alone,  one  inexperienced  in  reading 

radiographs  would  be  likely  to  say  that  two  teeth, 

the  lower  first  bicuspid  and  the  approximating  cuspid,  are  involved  in  an 

abscess,  since  the  evidence  of  bone  destruction  seems  to  include  the  apices 

of  the  roots  of  both  teeth. 

However,  the  application  of  the  electric  test  to  the  cuspid  proved  it 
to  have  a  vital  pulp  and  treatment  of  the  bicuspid  alone  effected  a  cure. 

Case :  The  evidence  of  bone  involvement  at  the 
Tig.  449.  apex  of  the  bicuspid  in  Fig.  449  is  so  slight  that  a 

definite  diagnosis  from  the  radiograph  alone  should 
not  be  made.  The  appearance  of  the  radiograph,  coupled  with  clinical 
signs  and  symptoms  and  the  fact  that  the  tooth  did  not  respond  to  the 
electric  test,  however,  enables  the  diagnostician  to  state  definitely  that  the 
pulp  in  the  tooth  is  not  vital  and  that  an  abscess  is  forming. 

41.  To  Make  Radiographs  of  Every  Tooth  in  the  Mouth  in 
All  Cases  Where  the  Teeth  Are  Bei-ng  Examined  to  Locate  Foci 
OF  Infection. 

In  cases  of  arthritis,  endocarditis,  neuritis,  gastritis,  becteremia  and 
other  "  systemic  "  diseases,  now  attributed  to  focal  infection,  it  is  not 
absolutely  necessary  to  radiograph  all  of  the  teeth  in  all  cases.  Where 
the  test  can  be  applied,  the  electric  test  for  pulp  vitality  may  be  made  and. 
if  positive,  a  radiographic  examination  is  usually  unnecessary,  unless  one 
wishes  to  observe,  for  example,  the  extent  of  bone  destruction,  due  to 
pyorrhea.  Thus  the  number  of  teeth  which  should  be  rayed  may,  in  some 
mouths,  be  greatly  reduced.  This  is  advantageous  to  the  patient  in  that 
the  cost  of  the  examination  is  reduced,  and  advantageous  to  the  operator 
in  that  he  reduces  the  dose  of  X-rays.  It  is  always  wise  to  expose  the 
patient  to  the  rays  as  little  as  possible,  and  likewise  it  is  the  sensible  thing 
for  the  operator,  for  his  own  welfare,  never  to  Hght  his  tube  unneces- 
sarily. Regions  from  which  teeth  are  missing  should  always  be  radio- 
graphed to  see  that  there  is  no  piece  of  gum-covered  root  or  unerupted 
tooth.  (See  Appendix  to  Chapter  VII  under  heading  "Oral  Foci  of 
Infection,"  page  416.) 

In  concluding  this  subject  of  radiographic  misinterpretation,  let  me 
repeat  what  I  said  at  the  outset  lest  I  be  grossly  misunderstood :  The 
use  of  the  radiograph  is  an  absolute  necessity  in  the  practice  of  dentistry. 
This  extensive  discussion  of  its  shortcomings  is,  to  the  man  who  can  see 


READING    RADIOGRAPHS  399 

past  his  nose,  a  recognition  of  the  fact  that  radiographs  must  be  used. 
It  is  not  a  harangue  against  their  use,  but  an  effort  to  stop  their  misuse 
and  abuse. 

I  realize  that,  in  the  foregoing  rather  exhaustive 
Oral  Toci  of  TnfCCtiOlU     consideration  of  the  interpretation  of  radiographs, 

I  have  not  answered,  to  the  point  of  setting  his  mind 
at  ease,  the  man  who  is  asking,  "  how  to  read  radiographs  "  for  the  very 
simple  and  apparent  reason  that  the  man  who  is  asking  "  how  to  read 
radiographs  "  not  only  wants  to  know  how  to  interpret  radiographs  but 
he  also  wants  to  know  how  to  treat  infection  revealed  by  radiographs. 
For  the  answer  to  this  latter  query  it  is  a  pleasure  to  be  able  to  refer  my 
readers  to  such  an  excellent  text  as  Thoma's  "  Oral  Abscesses." 

Allow  me,  however,  to  express  myself  briefly  on  this  subject.  The 
radiograph  gives  a  very  good  idea  of  the  amount  of  bone  destruction  in 
cases  of  dento-alveolar  abscess  and  pyorrhea  if  intelligently  interpreted. 
The  treatment  indicated  varies  greatly  according  to  the  amount  of  bone 
destruction.  But  granting  that  we  know  the  exact  amount  of  bone 
destruction,  different  operators  will  always  have  somewhat  different 
opinions  as  to  the  course  of  treatment  indicated.  One  operator  will 
excise  the  root  end  of  an  abscessed  tooth,  while  another  operator  will 
treat  by  ionization.  Both  operators  may  be  able  to  overcome  infection 
in  their  respective  ways.  The  treatment  indicated  depends  not  only  on 
the  condition  of  the  case  to  be  treated,  but  upon  the  personahty  and 
ability  of  the  operator.  It  is  not  good  sense  to  assume  that  the  same 
treatment  of  an  infected  tooth  is  indicated  regardless  of  the  operator. 
Some  operators  should  extract  teeth  which  other  operators  should  save. 
The  object,  when  treating  infected  teeth  and  contiguous  parts,  remains 
the  same,  namely,  eradication  of  infection.  Men  of  ordinary  ability  simply 
cannot  follow  the  methods  of  men  of  extraordinary  ability.  (Some 
results  of  treatment  of  abscesses  by  forcing  disinfectants  through  the 
canal  into  the  abscess  area,  by  ionization  and  by  root  resection  are  illus- 
trated in  the  Appendix  Chapter  XI,  which  will  give  the  reader  some  idea 
of  what  can  be  accomplished  by  these  methods  and  so  help  him  decide 
which  one  to  employ  in  certain  cases.) 

It  is  extremely  difficult  to  say  any  definite  thing  which  will  apply 
to  all  cases  in  a  general  way.  However,  I  believe  I  am  conservative  when 
I  make  this  statement :  If  a  tooth,  showing  bone  involvement  at  its  apex, 
is  to  be  treated  through  the  pulp  canal,  the  canal  must  be  open  through 
the  end ;  it  must  be  filled  just  to,  or  through,  the  end,  and  post-operative 


400  APPENDIX 

radiographs  must  be  made  at  intervals  of  two  or  three  months  for  about 
a  year,  or  until  the  abscess  cavity  is  filled  with  new  bone.  An  abscess 
cavity  which  shows  no  constructive  bone  change  at  all  at  the  end  of  six 
months  after  treatment  is  very  probably  still  a  source  of  infection.  As 
a  generality,  it  may  be  stated  that  if  new  bone  ever  will  be  built  into  an 
abscess  cavity,  some  reconstruction  will  take  place  within  the  first  six 
months  or  sooner,  and  the  reconstructive  change  will  be  practically  com- 
plete in  about  a  year. 

What  should  be  done  with  teeth,  the  canals  of  which  are  not  well 
filled  but  which  show  radiographically  no  bone  involvement  at  their 
apices?  is  a  most  disturbing  question.     The  idealist's  answer  would  be, 


Fig.   450.      Cement  fillings. 

"  insert  perfect  canal  fillings  or  extract  the  teeth."  This  advice  may, 
or  may  not,  be  good.  The  question  is  debatable,  with  everything  in 
favor  of  the  idealist,  however.  But  certainly,  when  a  patient  is  very 
seriously  ill  with  some  disease  which  might  be  attributed  to  a  focus  of 
infection,  all  of  the  pulpless  teeth  in  such  a  patient's  mouth  should,  at 
least,  have  a  well-filled  canal  or  they  should  be  extracted. 

It  is  not  idealistic,  perhaps,  but  it  is  practical,  to  be 
'rfttidlfioM^'  governed  in  the  treatment  of  infected  teeth  by  the 

patient's  physical  condition.  When  the  physical  con- 
dition is  good,  more  conservative  treatment  can  be  given  the  teeth.  When 
the  physical  condition  is  bad  and  the  patient  is  suffering  from  some 
disease  which  may  be  attributed  to  mouth  infection,  more  radical  treat- 
ment  (freer  surgical  interference)   must  be  given  for  mouth  infection. 


READING    RADIOGRAPHS 

K^ntblittd  Discourse. 


401 


The  writer  filled  canals  in  dissociated  teeth  with  fif- 

DO  the  UariOUS  Canal     teen  different  canal  fillino-  materials,  most  of  them 

Tflling  materials  .  ^         ah  %  ^1  .11 

Show  in  Radiographs  ?    proprietary  pastes.     All  of  these  materials  showed 

in  radiographs.     One  year  later  the  teeth  were  again 

radiographed  and  still  all  the   different  kinds   of  canal  filling  material 

showed  unchanged.     Had  the  teeth  been  in  the  mouth,  it  is  not  impos- 


Fig.    451.      Case   of  antral   empyema. 


sible  that  some,  at  least,  of  the  paste  canal  filling  materials  would  have 
sb.own  some  change  one  year  after  insertion.     That  the  presence  of  most 


402 


APPENDIX 


any  sort  of  canal  filling  can  be  demonstrated  radiographically  imme- 
diately after  its  insertion  is  a  fact,  but  whether  the  various  pastes,  cement 
and  paraffin  combination  fillings  can  be  observed  some  time  after  inser- 
tion, is  a  matter  as  yet  not  definitely  settled.    The  writer's  experience  at 


Fig.   451A.     The  arrows  point  to  a  shadow  which  has  the   appearance  of  a  tooth  just  starting 
to  form  in  the  antrum.     The  shadow  is  caused  by  the  dense  bone  along  the  lower  border  of  the 

malar   bone. 


this  time  leads  him  to  believe  that  some  cannot,  which  would  seem  to 
indicate  that  they  are  not  permanent. 

Gutta-percha  is  a  permanent  canal  filling  which  is  always  radio- 
graphically  visible. 

Cotton  with  iodoform  on  it  can  be  observed  radiographically  in 
canals. 

Paraffin,  as  a  canal  filling,  unmixed  with  anything  else,  can  not  be 
radiographed  successfully. 


READING    RADIOGRAPHS 


403 


$i1iciou$  Cement 
Tigure  450. 


Silicious  cement  is  more  penetrable  to  the  X-rays 
than  oxyphosphate  of  zhic,  colorless  copper  or  black 
copper  cements.     (See  Fig.  450.)     The  filling  on  the 


extreme  right  is  silicious  cement. 


Fig.    452. 


Case   of   suspected   frontal   sinus    or   antral   empyema, 
incisor  located. 


An    abscessed   upper   lateral 


404 


APPENDIX 


To  demonstrate  the  skill  one  may  acquire  from  read- 
€asc$  from  Practice.      ^^^?  ^  great  number  of  radiographs,  observe  Figure 

451.  It  is  highly  improbable  that  one  not  familiar 
with  head  radiographs  will  be  able  to  observe  anything  of  significance 


Fig.   452A.      From   the   time    of   the   first    acute    attack,    for    four    years,    this   tremendous    dental 
abscess  had  caused  the  patient  no  pain  whatsoever. 

in  this  plate,  yet  from  a  careful  study  of  it,  a  diagnosis  of  antral  empyema 
was  made,  the  verity  of  which  was  proved  by  operation. 

Figure  452  was  of  a  case  of  suspected  antral  or  frontal  sinus  em- 
pyema. The  frontal  sinuses  show  clear,  and  the  antra  are  clear  save  for  the 
shadow  cast  over  them  by  the  petrous  portion  of  the  temporal  bone. 


READING    RADIOGRAPHS 


405 


(Figure  452  was  made  from  a  pose  with  the  head  against  the  plate  as 
in  Figure  iii  but  with  the  X-rays  directed  diagonally  forward  from  a 
point  just  back  of  the  base  of  the  occipital  bone.  Such  a  pose  gives  a 
very  hazy  view  of  the  anterior  teeth,  a  good  view  of  the  frontal  sinuses 
and  a  view  of  the  antra  obscured  by  the  shadow  of  the  petrous  portion  of 
the  temporal  bone.)  Observe  a  small  spot  at  the  apex  of  the  lateral  incisor 
on  the  right.  A  small  intra-oral  radiograph  was  made  and  shows  an  abscess 
cavity  at  the  apex  of  this  lateral.  The  patient  would  not  consent  to  root 
resection;  the  lateral  was  therefore  extracted  and  the  pus  discharge 
from  the  nose  ceased.      (See  Figure  425.)      The  diagnosis  in  this  case 


Fig.   453.      Diagnostic    illuminating  or  view  box,  for  observing  X-ray  negatives. 


resulted  from  a  thorough  study  of  the  large  plate  (Figure  452),  in  which 
the  suspicious  area  at  the  apex  of  the  lateral  was  first  observed.  A  care- 
less, or  thoughtless  examination  of  the  antero-posterior  plate  would  have 
resulted  in  failure  to  make  the  correct  diagnosis. 


CDronic  7lb$cc$$ 
and  Pain. 


It  is  a  well-known  fact  among  most  dentists  that  a 
chronic  abscess  may  exist  without  causing  any  pain 
or  any  local  sensation  at  all  for  that  matter.  But  all 
dentists  do  not  know  this  as  well  as  they  might,  nor  do  near  all 
physicians ;  and  the  public  scarcely  knows  it  at  all.     It  is  a  fact  which 


4o6 


APPENDIX 


should  be  repeated  again  and  again.  I  have  seen  a  case  recently  with 
half  of  the  palatal  portion  of  the  superior  maxillary  bone  destroyed, 
the  only  symptom  given  by  the  patient  being,  "  one  side  of  the  roof  of 
my  mouth  seems  a  little  softer  than  the  other."  When  explaining  these 
things   to   patients   I    have    found   that   I   can   overcome    incredulity   by 


Fig-.  454.  Special  dental  view 
box  for  observing  small 
X-ray    negatives. 


Fig.    4.55.       Special    dental    device    for    observing    dental    X-ray 


directing  attention  to  the  well-known  fact  that  large  parts  of  the  lungs 
may  be  lost  from  tuberculosis  with  little  or  no  pain  in  the  lungs.  (See 
Fig.  452 A.) 

Figure  453  is  a  type  of  view  box  which  has  entirely 
UiCW  Boxes.  replaced  the  type  illustrated  in  Figure  122. 

Special    dental    view    boxes    and    illuminating 
devices  are  illustrated  in  Figures  454,  455  and  456. 

Dr,  Edmund  Kells,  Jr.,  ofifers  a  scheme  for  marking 
niarKing  negatives,      small  film  negatives   for  identification  by  punching 

a  small  hole  in  the  negative  with  a  plate  punch  and 
tying  a  string,  with  a  small  price-tag-like  label  on  it,  to  the  negative 
which  will  certainly  eliminate  the  possibility  of  "  mixing  "  negatives  by 
getting  the  negatives  from  one  patient's  envelope  into  another  patient's 
envelope. 


READING    RADIOGRAPHS 


407 


I  would  earnestly  advise  that  some  sort  of  filing  box 
Tiling  Boxes  cr  qj-    cabinet    be    used    by    all    who    use    radiographs. 

Otherwise  negatives  will  be  lost  or  so  chaotically  dis- 
tributed about  the  office  that  they  can  never  be  found  when  needed. 

While  it  is  true,  in  a  general,  inaccurate  way,  that 
X-rays  penetrate  substances  inversely  in  proportion 
to  their  density,  it  is  rather  a  loose  way  of  stating  the 
action  of  the  rays.  Dr.  Ottolengui  has  accordingly  coined  the  following 
words :     Radioparent   and    radioparency,    radiolucent    and    radiolucency, 


Dr.  Ottolengui's 
new  moras. 


Fig.    456.      Special     dental     illuminating     device  _  for     displaying     and     observing     dental     X-ray 

negatives. 

radiopaque  and  radiopacity  from  the  words  transparent  and  trans- 
parency, translucent  and  translucency,  opaque  and  opacity.  Thus  we 
might  speak  of  a  shadow  in  a  radiograph  something  like  this :  "  The 
small  radiopaque  area  is,  I  believe,  a  piece  of  tooth  root."  Or  instead 
of  referring  to  a  rarefied  area  at  the  apex  of  a  tooth  we  would  say: 
"There  is  a  radioparent  or  a  radiolucent  (depending  on  the  degree  of 
X-ray  penetration)  area  at  the  end  of  such  and  such  a  tooth." 
It  seems  to  me  these  words  will  prove  to  be  most  useful. 


4o8 


APPENDIX 


O 


^ 


^^ 


13 


Chart    A  A 


READING    RADIOGRAPHS  409 

Illustrating  different  sorts  of  canal  fillings  as  seen  in  radiographs 

The  arrangement  is  somewhat  in  the  order  of  the  excellency  of  the 
filling. 

No.  I.  Canals  filled  full.  Three  apical  foramina  filled  just  through 
the  end  of  the  root. 

No.  2.  Canal  filled  just  through  end.  Auxiliary  canal,  to  the  mesial, 
filled. 

No.  3.  Canal  filling  material  encapsulating  the  end  of  root.  We 
see  through  the  encapsulating  material.  When  the  material  encapsulating 
the  root  is  thicker — as  it  usually  is — the  radiograph  appears  to  show  a 
body  of  gutta-percha  beyond  the  end  of  the  root  instead  of  a  cap  over  it. 

No.  4.  Root  end  encapsulated  and  a  little  body  of  gutta-percha  in 
periapical  space. 

No.  5.  Canal  filling  material  through  end  of  root  and  filling  into 
cancellous  places  in  bone.     More  material  through  than  desirable. 

No.  6.  Gutta-percha  point  passing  through  apical  foramen  intact, 
differing  from  Nos.  3,  4  and  5  where  mushy  eucalyptopercha  or  chloro— 
percha  has  "  mushed  "  or  "  oozed  "  through  apical  end.  Not  so  desirable 
because  perhaps  apical  foramen  is  not  filled  full — perhaps  gutta-percha 
point  just  passes  through  without  filling  the  opening  through  which  it 
passes. 

No.  7.  Too  much  canal  filling  too  far  through  apical  foramen.  In 
this  particular  case,  however,  no  evidence  of  irritation  developed. 

No.  8.  The  practice  of  filling  abscess  cavities  full  of  the  Callahan 
gutta-percha-rosin  mixture  is  being  tried  by  some.  The  expediency  of 
this  course  has  neither  been  proved  nor  disproved. 

No.  9.  This  canal  filling  very  probably  reaches  the  end  of  the  root 
of  the  tooth,  but  we  cannot  be  certain  of  this  from  the  appearance  of 
the  radiograph.  We  cannot  be  absolutely  certain  any  canal  filling  reaches 
the  end  unless  a  little  passes  through. 

No.  10.  These  canal  fillings  very  probably  do  not  quite  reach  the 
end  of  the  root  but  we  cannot  be  absolutely  certain  they  do  not. 

No.  II.  The  "cork  screw"  or  "buckled"  canal  filling  which  does 
not  fill  the  canal  solid  full.  ...  A  very  faulty  filhng. 

No.  12.  A  filling  of  one  gutta-percha  point  which  neither  fills  the 
canal  full  nor  reaches  the  end  of  the  root. 

No.  13.  A  filling  of  one  gutta-percha  point  which  reaches  well 
toward  the  end  of  the  root  but  does  not  fill  the  canal  full.  ...  A  very 
faulty  filling. 

No.  14.  A  point  inserted  through  a  perforation  between  the  roots 
of  a  lower  molar.  We  may  have  little  respect  for  the  operator's  ability 
who  did  this ;  but  he  tried,  and  so  we  have  more  respect  for  him  as  a  man 
than  for  the  operator  with  greater  ability  who  doesn't  even  try. 


4IO 


APPENDIX 


! 


ir^ 


# 


4. 


4i 


ii 


B 


M^ 


\l 


Chart  B  B 


READING    RADIOGRAPHS  411 

0bart  BB 

Illustrating  different  degrees  of  evidence  of  infection  seen  in  radiographs 

Nos.  I  and  2.  No  radiographic  evidence  whatever  of  infection. 
The  canal  fillings  are  perfect  as  far  as  we  are  able  to  see  and  the  bone 
in  the  apical  region  has  the  appearance  of  healthy  bone. 

No.  3.  No  definite  evidence  of  infection.  However  we  cannot  be 
as  certain  that  the  canal  is  filled  to  the  end  as  in  the  cases  of  Nos.  i 
and  2,  where  a  little  canal  filling  material  passes  through  the  end  of 
the  root.    There  is  no  evidence  of  bone  change  in  the  periapical  tissues. 

No.  4.  The  only  evidence  of  infection  is  the  evidence  that  the  canal 
filling  does  not  reach  the  end  of  the  root.  There  is  no  periapical  bone 
change. 

No.  5.  Like  No.  4,  the  evidence  of  infection  is  only  the  evidence 
that  the  canal  filling  does  not  reach  the  end  of  the  root.  In  this  case 
we  see  also  the  unfilled  part  of  the  canal  standing  open.  Perhaps  the 
lumen  of  the  unfilled  part  of  the  canal  in  No.  4  is  very  small,  but  we 
know  it  is  large  in  No.  5. 

No.  6.  Though  the  canal  filling  reaches  well  toward  the  end  of  the 
canal,  it  does  not  fill  the  canal  full  and  is,  therefore,  a  faulty  canal 
filling.  The  only  evidence  of  infection  is  the  evidence  that  the  canal 
filling  is  imperfect. 

Nos.  7  and  8.  The  canal  fillings  are  imperfect  and  there  is  evi- 
dence of  bone  change  in  the  apical  region.  The  evidence  of  bone 
change — rarefication  and  sclerosis — is  so  slight  that  it  would  not  be 
looked  upon  as  evidence  of  infection  if  it  were  not  for  the  fact  that  the 
teeth  are  pulpless  and  the  canal  fillings  faulty. 

No.  9.  Definite  evidence  of  bone  destruction  and  hypercementosis, 
both  indicative  of  infection.  However,  the  canal  filling  seems  to  be 
perfect.  The  history  of  the  case  governs  my  opinion  here.  The  tooth 
has  just  been  treated;  there  has  been  no  time  for  bone  reconstruction  to 
occur. 

No.  10.  The  evidence  of  infection  is  quite  definite ;  canal  filling 
is  faulty  and  there  is  destructive  bone  change  in  the  apical  region. 

No.  II.  Definite  evidence  of  infection,  (i)  faulty  canal  filling, 
(2)  bone  destruction,  (3)  osteosclerosis. 


412 


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s 


I 


i       Pi    C^4 


Chart  CC 


READING   RADIOGRAPHS  413 

v,un  0  0 

Illustrating  how  the  radiograph  helps  the  operator  to  determine  the  nature 
of  the  treatment  indicated 

No.  I.  Considering  the  tooth  involved  and  the  sHght  amount  of 
bone  change,  treatment  through  the  canals  would  be  the  writer's  choice. 

No.  2.  Different  operators  would  disagree  as  to  the  treatment 
indicated.  Some  would  treat  through  the  canals,  others  would  resect 
and  curette.  Certainly  the  resection-curettement  operation  is  a  more 
reliable  means  of  eradicating  infection,  but  I  have  seen  cases  like  No.  2 
yield  to  treatment  through  the  canals  and  show  a  bone  reconstruction 
following  such  treatment. 

No.  3.  Compared  with  No.  2,  the  resection-curettement  operation 
is  becoming  more  imperative. 

No.  4.    Root  resection  is,  I  believe,  definitely  indicated  here. 

Nos.  5  and  6.  Treatment  through  canals  contra-indicated.  Prog- 
nosis for  root  resection,  somewhat  doubtful. 

Nos.  7  and  8.  Prognosis  for  root  resection,  very  doubtful.  Too 
much  bone  destruction  too  far  down  on  the  mesial  in  No.  7,  and  too 
much  loss  of  osseous  tissue  at  the  cervical  in  No.  8. 

No.  9.  Prognosis  for  treatment  through  canals  good,  if  the  canals 
can  be  opened  to  the  end. 

No  10.  What  the  writer  now  considers  as  about  the  limit  of  the 
extent  of  bone  destruction  at  the  apex  of  a  molar  which  may  be  treated 
successfully  through  the  canals. 

No.  II.  The  number  of  teeth  involved  often  governs  the  treat- 
ment indicated.  I  should  say,  arbitrarily,  extract  the  molars;  treat  the 
bicuspid. 

N.  B.  In  the  foregoing  the  writer  has  not  taken  into  considera- 
tion the  physical  condition  of  the  patient.  In  practice  this  is  a  most 
important  factor. 


414 


APPENDIX 


I 


.:j> 


T 


7 


Chart  D  D 


WORKING    DENTAL    RADIOGRAPHS  415 

0bart  D  D 

Illustrating  a  number  of  different  cases  where  extraction  is  indicated 

No.  I.  The  abscess  is  so  large — i.  e.,  there  is  such  extensive  bone 
destruction — the  case  looks  as  though  it  might  be  syphilhtic,  but  is  not. 
Extraction  of  all  the  teeth  involved  was  deemed  the  best  procedure. 

No.  2.  So  much  bone  destruction  that  treatment  of  any  sort 
calculated  to  lead  to  the  retention  of  the  tooth  would  probably  fail  to 
eradicate  infection. 

No.  3.  The  bone  about  the  distal  root  of  the  first  molar  is  entirely 
gone;  the  canal  fillings  in  the  mesial  root  are  faulty  and  probably  could 
not  be  made  perfect.  (It  is  very  difficult  to  open  canals  of  molars  to 
the  end  when  opening  the  tooth  for  the  first  time.  When  the  canals 
have  already  been  partially  filled  by  a  previous  operator,  the  chance  of 
opening  such  canals  to  the  end  is  greatly  lessened.; 

Two  perforations  with  canal  filling  passing  through  them  in  the 
second  molar. 

Extraction  of  both  first  and  second  molars  indicated. 

No.  4.  The  first  bicuspid  is  hopelessly  diseased ;  the  bone  de- 
struction at  the  apex  extends  down  along  the  sides  of  the  root  to  the 
cervical. 

No.  5.  The  extraction  of  the  central  incisor  is  indicated  because 
there  is  so  much  destruction  of  its  root  that  root  resection  would  very 
probably  be  unsuccessful. 

No.  6.  Only  by  extraction  can  the  abscess,  caused  by  the  post 
passing  through  the  distal  side  of  the  second  bicuspid,  be  cured. 

No.  7.  There  were  only  ten  teeth  left  in  this  mouth.  All  of  them 
showed  bone  destruction  at  the  apex  or  at  the  cervical,  or  at  both 
places   (the  lateral). 


APPENDIX  TO  CHAPTER  VII 

Uses  of  Radiodrapby  in  Dentistry. 

The  temptation  to  submit  more  radiographs  to  illustrate  the  uses 
of  the  radiograph  in  dentistry  is  intense.  I  could  now  illustrate  some 
of  the  uses  with  better  radiographs  than  are  shown  in  Chapter  VII,  but 
most  of  the  uses  are  already  sufficiently  well  illustrated  to  teach  the  prin- 
ciple of  the  application  of  the  radiograph,  and  that  is  as  far  as  I  should 
go,  otherwise  there  would  be  no  limit  to  the  number  of  radiographs  which 
might  be  shown,  each  having  some  interesting  peculiarity  of  its  own. 

In  other  words,  I  will  not  attempt  to  exhaust  the  subject  for  reasons 
so  cleverly  set  forth  in  the  following  excerpt  from  "  Life  " :  "  Writers 
should  early  learn  not  to  try  to  exhaust  a  subject.  If  there  is  one  thing 
above  another  thing  that  a  subject  will  not  stamd  for  it  is  to  be  exhausted. 
It  is  the  one  tireless  thing  extant.  In  every  other  way  subjects  are  ami- 
able and  tractable.  If  you  go  at  a  subject  in  the  right  spirit  you  can  say 
nearly  anything  you  wish  about  it,  but  immediately  you  try  to  get  a  rope 
around  a  subject's  neck  and  chase  it  around  a  ring  until  it  is  absolutely 
used  up,  the  said  subject  takes  on  a  dry,  dogged,  stubborn  air  and  re- 
fuses to  be  interesting,  and,  of  course  a  writer  who  cannot  keep  his  sub- 
ject interesting  is  lost. 

"  Think  of  the  most  uninteresting  books  you  ever  read.  They  were 
written  by  men  who  quite  evidently  sat  down  with  the  mental  resolution : 
'  Now  I'll  just  clean  up  on  this  subject  once  for  all,  so  that  it  will  hence- 
forth be  clear  to  all  posterity,  even  unto  the  day  of  judgment.'  But,  of 
course,  no  such  aim  was  ever  realized.  The  only  sure  result  of  trying  to 
exhaust  a  subject  is  to  prove  that  it  is  exhaustless." 

The  subject  of  the  Uses  of  the  Radiograph  in  Dentistry  is  certainly 
exhaustless ;  so  I  shall  be  satisfied  to  treat  the  subject  in  this  appendix  as 
concisely  as  possible. 

Perhaps  the  most  extensive  use  of  the  radiograph 
Tad  ot  Tnf^ction  ^"  ^^^  practice  of  dentistry  today  is  as  a  means  of 
examining  the  mouth  for  infection  in  cases  of  bac- 
teremia, arthritis,  neuritis,  endocarditis,  gastric  ulcer,  appendicitis,  en- 
teritis, dermatitis,  cholecystitis,  nephritis  and  other  constitutional  dis- 
eases ;  also  in  cases  of  diseases  of  the  eye,  ear,  nose  and  throat,  which  we 
now  believe  may  be  caused  by  some  focus  of  infection.  For  this  purpose 
the  use  of  the  radiograph  is  absolutely  indispensable. 

The  practice  of  simply  making  ten  film  radiographic  negatives  and 

416 


USES    OF   RADIOGRAPHY   IN   DENTISTRY  417 

then  calling  it  a  complete  examination  of  the  mouth  is  a  much  abused  one. 
Usually  it  is  impossible  to  obtain  good  radiographs  of  all  of  the  teeth 
on  ten  negatives,  and  often  it  is  not  absolutely  necessary  to  make  radio- 
graphs of  all  of  the  teeth.  (It  is  sometimes  more  necessary  to  ray  all  the 
teeth  in  other  classes  of  cases,  such  as  obscure  neuralgias,  for  example, 
than  it  is  when  the  examination  is  made  in  a  search  for  infection.) 

It  has  been  said  that,  in  many  cases  where  a  search  is  being  made 
for  oral  infection,  it  is  "  entirely  unnecessary  "  to  radiograph  all  of  the 
teeth.  I  cannot  agree  that  it  is  "  entirely  unnecessary,"  though  it  is  very 
often  largely  unnecessary.  A  radiodontist  of  keen  judgment  may  elim- 
inate certain  parts  of  mouths  from  the  radiodontic  examination  and  not 
make  a  mistake  by  so  doing  once  in  fifty  cases,  but  the  fact  that  it  is 
possible  that  he  may  make  a  mistake  at  all  should  keep  us  from  condemn- 
ing the  practice  of  radiographing  all  teeth  as  "  entirely  unnecessary." 

To  make  an  examination  of  the  mouth  to  determine  whether  or  not 
the  teeth  and  jaws  are  a  source  of  infection,  the  use  of  the  radiograph  is 
only  a  part — true,  the  most  important  part  but,  nevertheless,  only  a  part 
— of  the  examination. 

Careful  ocular,  instrumental  and  digital  examination  should  be  made. 
Then  the  teeth  should  be  tested  for  pulp  vitality  with  the  electric  test  and 
records  made  of  the  result  of  these  tests.  Now  radiograph,  at  least,  the 
following  regions :  ( i )  Regions  from  which  teeth  are  missing,  to  locate 
pieces  of  roots  or  unerupted  teeth.  (2)  Teeth  which  do  not  respond  to 
the  electric  test  and  teeth  which  cannot  be  satisfactorily  tested  with  the 
electric  test.  (This  always  includes  crowned  teeth.)  (3)  Teeth  af- 
fected with  pyorrhea,  to  observe  the  extent  of  the  loss  of  osseous  tissue. 
(4)   Any  region  of  tenderness,  localized  pain  or  abnormal  appearance. 

An  area  of  infection  frequently  overlooked  is  illustrated  in  Fig.  457 
In  a  case  such  as  Fig.  457,  pus  can  often  be  pressed  into  view  with  the 
finger,  pressing  with  the  index  finger  from  below  upward  on  the  lingual 
and  just  to  the  distal  of  the  third  molar.  Because  there  is  less  distortion, 
lesions  like  the  one  illustrated  in  Fig.  457  can  be  seen  to  better  advantage 
in  extra-oral  radiographs  than  in  the  intra-oral  ones. 

Dr.  Risen  makes  it  his  practice  to  radiograph  both  sides  of  the  mouth 
on  plates  first,  then  re-ray  on  a  film  any  suspicious  areas  found  in  the 
plate  if  necessary  to  get  a  better  view.  This  practice  is  certainly  to  be 
commended. 

I  have  made  the  statement  repeatedly  that  an  im- 

cfifth  pacted  tooth  may  cause  no  trouble  at  all  or  it  may 

produce  the  most  disastrous  results.     Allow  me  to 

illustrate  this :    Figure  458A  and  458B  show  two  impacted  upper  cuspids 


4i8 


APPENDIX 


in  the  same  mouth.  One  (Fig.  458A)  shows  no  evidence  of  pathologic 
condition  of  the  surrounding  tissues  while  the  other  (Fig.  458B)  shows 
a  great  deal  of  bone  destruction,  due  to  suppuration.     However,  an  un- 


Fig.   457.      The    arrow   points    to    a   V-shaped   area,   indicating  bone   destruction   back    of    a   lower 
third  molar.      (Eisen   and   Ivy.) 


Fig.    458A   and   458B.      Unerupted   cuspids,   both   in   the   same   mouth,   one   causing   much   bone 

destruction,  the  other  none. 

erupted  tooth  must  be  looked  upon  always  as  a  source  of  possible  sup- 
puration, even  when  the  radiograph  shows  no  destruction  of  bone. 


Unerupted  Cuspid 
made  to  €rupt. 


Tid.  459a. 


Figure  459  is  the  same  case  illustrated  in  Figures 
150,  151  and  152  with  the  cuspid  in  its  proper 
place. 

Never  having  seen  the  case  illustrated  in  Fig.  207, 
the  writer  certainly  is  not  in  a  position  to  take  issue 
with  Dr.  Rhein,  who  treated  the  case,  and  Dr.  Otto- 
lengui,  who  wrote  the  history  of  the  case  on  pages  195  and  196.  How- 
ever, I  may  say  simply  this ;  the  shadow  over  the  cuspid  illustrated 
in.  Fig.  207  has,  to  me,  the  radiographic  appearance  of  being  the  antrum. 
Figure  459A  is  a  case  having  a  similar  appearance  to  Fig.  207.  In  Fig 
459A  I  feel  quite  certain  that  the  shadow  over  the  cuspid  is  the  antrum. 


USES   OF    RADIOGRAPHY    IN   DENTISTRY  419 

I  can  perhaps  impress  you  with  the  value  of  making 
Root  Kw^Ctfon  €a$($.     radiographs  before  operating  to  excise  root  ends  by 

relating  this  experience.  Dr.  Carl  D.  Lucas,  who 
was  to  give  a  clinic  on  apical  excision  before  the  Indianapolis  Dental  So- 
ciety, asked  that  a  patient  be  selected  for  him  from  the  Indiana  Dental 
College  clinic.  The  demonstrators  in  the  college  clinic  were  advised  of 
this  and  asked  to  select  a  suitable  case  and  send  it  to  me  for  a  radio- 
graphic examination.     Thus,  the  cases  which  came  to  me  were  those  in 


Fig.   459.      The  same  case  illustrated  in   Figs.        Fig.   459A.      The   shadow   of  the   antrum   over 
150,    151    and    152,    after    eruption    of    the  the   cuspid    gives    the    cuspid    somewhat    the 

cuspid.     (Radiograph  by  Kells.)  appearance  of  being  abscessed. 

which  the  symptoms  were  such  as  to  indicate  apical  excision.  Apical 
excision  was  seen  to  be  contra-indicated,  however,  in  the  first  case,  when 
the  radiograph  showed  the  root  of  the  tooth  to  be  abnormally  short;  in 
the  second  case,  when  the  radiograph  disclosed  the  presence  of  a  perfora- 
tion ;  and  in  the  third  case  in  which  the  destruction  of  bone  was  too  ex- 
tensive. In  the  fourth  case,  the  radiographic  finding,  indicated  apical  ex- 
cision, thus  finally  substantiating  the  conclusions  based  on  a  knowledge  of 
symptoms.  In  the  light  of  this  unusual  but  instructive  experience  I  would 
insist  that  the  operator  should  always  make  a  radiographic  examination 
before  operating  to  excise  a  root  end. 

Figure  460  shows  a  malposed,  unerupted,  partially 
facial  TfStU  a  €a$C$.      formed  upper  second  bicuspid.     In  this  case  the  pus 

discharged  just  beneath  the  eye.  Removal  of  the 
malposed  bicuspid  effected  a  cure.  Figure  461  is  a  photograph  of  the  case 
one  month  after  operation.     (Operators,  Drs.  Page  and  Cofield.) 

The  use  of  radiographs  in  cases  of  fistulas  pointing  on  the  face  is 
attended  almost  always  with  the  most  gratifying  results.  While  the  radio- 
graph will  usually  show  some  bone  involvement  in  these  cases  it  should 
be  remembered,  however,  that  infection  of  the  soft  parts  surrounding 


420 


APPENDIX 


a  lower  third  molar  may  result  in  the  formation  of  a  fistula  on  the  face 
with  practically  no  bone  involvement  at  all.    Neither  should  one  lose  sight 


Fig.    460.      Malposed,   unerupted,   partially 
formed   upper   second   bicuspid. 
Photograph   of   case. 
Fig.    461. 


Fig.  461.      Post   operative   photograph   of   facial 
fistula   case.      Scar    under    eye.      See    Fig.    460. 


of  the  fact  that  an  ordinary  skin  abscess — i.e.,  a  boil — may  have  a  clin- 
ical appearance  somewhat  similar  to  an  abscess  of  dental  origin. 

I  have  been  surprised  to  find  radiographs  of 
hidden  Dental  Canes,  such  value  in  locating  hidden  carious  cavities  in 
TiflS.  462,  463  ana  464     ^g^^^ 

Figure  462  is  a  case  in  which  the  patient  was  suffering  consider- 
ably. The  pain  seemed  to  be  localized  in  either  the  second  bicuspid  or 
the  first  molar.  The  radiograph  shows  nothing  wrong  with  the  second 
bicuspid,  an  abscess  at  the  mesio-buccal  root  of  the  first  molar  and,  most 
important  of  all  from  the  standpoint  of  relieving  pain,  a  carious  cavity 
in  the  distal  of  the  second  molar.  The  cavity  was  entirely  covered  with 
gum  tissue,  When  access  was  gained  to  it,  it  was  found  that  the  pulp  was 
exposed.  A  sedative  treatment  was  applied  and  pain  was  relieved 
immediately. 

Figure  463  shows  caries  at  the  cervical  margins  of  the  fillings  in  the 
distal  of  both  the  first  and  second  molars.  Such  cavities  as  these  are  very 
seldom  found  at  all  unless  located  radiographically.  (In  this  particular 
case,  Figure  463,  both  of  the  molars  are  abscessed.) 

The  history  of  Figure  464  is  rather  long  but  quite  interesting.  A 
man  of  middle  age,  multimillionaire,  awoke  one  morning  with  the  tooth- 


USES    OF   RADIOGRAPHY   IN   DENTISTRY 


421 


ache.  Straightway  he  visited  a  dentist,  who  examined  his  mouth,  told 
him  there  was  nothing  the  matter  with  his  teeth  and  that  he  had  neuralgia. 
The  patient,  still  believing  he  had  toothache,  visited  another  dentist  who 
examined  his  mouth  and  told  him  in  substance  the  same  thing.  And  the 
patient  who  still  believed  he  had  the  toothache  visited  a  third  dentist  who 


Fig.    462.       Gum-covered    carious    cavity 
distal    of    upper    second    molar. 


40.'!.     Fillings   failing   at   the   cervical 
margin. 


Fig.    464.      Hidden   carious    cavity    in    distal    of   lower    first    molar. 

like  the  others,  examined  his  teeth  and  told  him  his  teeth  needed  no  treat- 
ment. In  despair,  since  his  dentists  had  failed  him,  the  man  next  visited 
a  bar-tender  and  then  another  bar-tender,  and  another,  and  another,  until 
his  friends  took  him  to  the  hospital  that  he  might  recover  from  delirium 
tremens.  In  due  time  he  recovered  from  his  delirium  and  as  soon  as  he 
did,  he  complained  of  the  toothache.  A  dentist  was  called  in.  He  ex- 
amined the  mouth  and  found  nothing  wrong  with  the  teeth.  It  happens, 
however,  that  this  particular  dentist  is  a  radiodontist  of  no  mean  ability, 
and,  so  he  asked  to  be  permitted  to  make  a  radiograph  of  the  region  where 
the  pain  seemed  to  be  located.  This  was  granted  promptly — though  at  the 
time  all  this  occurred  very  few  radiographs  of  teeth  were  being  made 
— for  the  physicians  in  charge  of  the  case  were  helpless. 

Figure  464  was  made  and  shows  a  carious  cavity  in  the  distal  of  a 
lower  first  molar !    The  case  was  simply  one  of  pulpitis !  There  are  doubt- 


422  APPENDIX 

less  those  who  will  say  that  the  cavity  should  have  been  discovered 
without  the  aid  of  the  radiograph,  by  instrumentation.  Perhaps,  but,  the 
fact  remains,  it  was  not.    And  so  impressed  were  the  medical  men  with 


Fi?.  4(;r).     Slight  destruction  of  osseous  tissue 

in  apical  region  of  lower  first  molar  follow-         Fig.    4(i(;.      Case   in   which  the   patient   suffered 
ing  use   of  arsenic.  from  attacks  of  sneezing. 

the  dentist  who  finally  made  a  diagnosis  and  cured  the  patient,  they  put 
him  on  the  hospital  staff,  a  member  in  full  standing;  a  thing  that  had 
never  happened  to  a  dentist  in  that  city  before. 

Figure  465  illustrates  a  slight  bone  destruction  at 
CbC  €ffCCt  Of  Jlr$cniC.  the  apices  of  the  roots  of  a  lower  first  molar  imme- 
diately following  devitalization  of  the  pulp  with  ar- 
senic. However,  I  cannot  state  definitely  that  the  slight  bone  destruction 
is  not  due  to  infection,  for  I  do  not  know  in  detail  the  conditions  under 
which  the  work  was  done. 

Symptoms :  Periodic  sneezing  attacks.  The  radio- 
Ucry  Unusual  Ca${.  graph  (Figure  466)  shows  an  abscess  of  an  upper 
central  incisor,  communicating  with  an  abscess 
sinus  in  the  apical  region  of  the  extracted  lateral.  Up  to  the  present 
time,  I  have  been  unable  to  hear  from  the  case  since  the  radiographic 
examination,  but  I  feel  quite  certain  the  condition  of  the  teeth  could  be 
responsible  for  the  sneezing  attacks. 

It  used  to  be  the  writer's  opinion  that  a  piece  of  root 
Pieces  of  toOtb  Root,  would  always  "  work  "  to  the  surface  of  the  gum  in 
time.  Radiographic  experience  is  teaching  me,  how- 
ever, that  not  infrequently  the  gum  heals  over  tooth  roots  and  they  remain 
in  the  jaws  for  years  without  appearing  at  the  surface  of  the  gum  tissue. 
Such  roots  are  usually  a  source  of  irritation  and  infection,  though  not 
always.   . 


APPENDIX  TO  CHAPTER  VIII 

Cbc  Hnmr  of  tbe  X-Rays. 

The  following-  factors  must  be  considered  when  determining  the  dose 
of  the  X-rays  :  (i)  The  time  of  exposure.  (2)  The  milliamperage  passing 
through  the  tube.  (3)  The  distance  between  target  and  skin.  (4)  The 
action  of  a  filter.  (5)  The  quality  of  the  X-rays.  (6)  The  temperature 
of  the  X-ray  tube,  (7)  The  kind  and  working  condition  of  the  X-ray 
machine.     (8)  The  sensitivity  of  the  skin  exposed. 

It  will  be  seen  from  the  foregoing  that  the  problem  of  administering 
exact  doses  of  the  X-rays  is  one  fraught  with  great  difficulties.  It  is 
the  writer's  opinion  that  general  practitioners  of  dentistry  and  medicine 
should  not  use  the  X-rays  for  therapeutic  purposes  unless  they  are  willing 
to  give  the  matter  the  great  amount  of  study  necessary  to  enable  them 
to  administer  definite  doses. 

It  is  the  writer's  further  opinion  that  both  the  general  practitioner  of 
dentistry  and  medicine  may  find  it  to  their  advantage  to  use  the  X-rays 
for  radiographic  purposes.  When  using  the  X-rays  for  radiographic 
purposes  it  is  not  necessary  that  the  operator  know  all  there  is  to  be 
known  about  dosage.  He  should,  however,  know  enough  so  he  will  not 
expose  his  patients  to  the  point  of  producing  dermatitis. 

It  is  with  the  idea  of  imparting  only  such  knowledge  as  will  enable 
men  to  practice  radiodontia  without  danger  of  producing  X-ray  derma- 
titis that  we  take  up  a  consideration  of  X-ray  dosage.  Only  the  most  im- 
portant and  most  variable  factors  governing  dosage  will  be  considered. 

The   efifect   of   the   X-rays   on   the   skin   varies   di- 
andmfuiamu^raat        rectly  according  to  the  length  of  time  of  exposure ; 
thus,  other  things  remaining  the  same,  the  effect  is 
twice  as  great  if  the  exposure  is  two  seconds  as  it  would  be  if  the  ex- 
posure were  for  one  second. 

The  effect  of  the  X-rays  on  the  skin  also  varies  directly  according  to 
the  number  of  milliamperes  passing  through  the  tube ;  for  example,  other 
things  remaining  the  same,  10  milliamperes  produce  twice  the  effect  pro- 
duced by  5  milliamperes. 

To  obtain  the  same  effect  on  the  skin  as  the  time  is  lessened  the  milli- 
amperage must  be  increased,  or  as  the  milliamperage  is  lessened  the  time 
must  be  increased.  For  example,  10  milliamperes  for  6  seconds  will  have 
practically  the  same  effect  as  6  milliamperes  for  10  seconds.  In  other 
words,  the  milliampere-second  dose  is  the  same,  i.e.,  60  milliampere- 

423 


424  APPENDIX 

seconds.  The  milliampere-second  unit  is  obtained,  recall,  by  multiplying 
the  number  of  milliamperes  passing  through  the  tube  by  the  number  of 
seconds  exposure. 

Though  it  would  not  do  for  the  X-ray  therapeutist,  the  milliampere- 
second  is  perhaps  the  best  unit  of  measurement  of  X-ray  dosage  for  the 
radiographer. 

The   effect   of  the   X-rays   on   the   skin   varies   in- 

'St^il^llfliPilM.tS"        versely  with  the  square  of  the  distance  or,  to  state 
varget  ana  Skin.        ,       -^      ,  .      ,...^      ,     .        ,  ,     .     , 

the  same  thing  diiierently,  m  order  to  obtam  the  same 

effect  on  the  skin  the  size  of  the  milliampere-second  dose  varies  directly 
with  the  square  of  the  distance.  To  elucidate :  The  dose  necessary  to 
produce  erythemia  of  the  skin  of  the  face  with  the  skin-target  distance 
8  inches  is  about  i2ck)  milliampere-seconds.  With  the  skin-target  dis- 
tance increased  to  i6  inches  the  erythemia  dose  is  about  4800  milliampere- 
seconds.  This  conclusion  is  reached  as  follows :  the  square  of  8  is  64, 
the  square  of  16  is  256,  256  is  four  times  as  much  as  64.  Therefore,  the 
dose  at  16  inches  is  four  tim.es  as  much  as  at  8  inches,  for  the  dose  neces- 
sary to  produce  the  same  effect  varies  directly  with  the  square  of  the 
distance. 

The  use  of  a  filter  of  one  millimeter  of  aluminum 
CbC  filter.  necessitates  doubling  the  dose  to  get  the  same  skin 

effect. 


We  are  now  ready  to  consider  a  limit  of  the  dose 
''^"of  Patfcntr"'*^  °^  X-rays  to  be  given  to  radiodontic  patients.  I 
would  suggest  that  operators  never  exceed  one-half 
the  erythemia  dose. 

Suppose  now,  for  example,  that  the  distance  between  the  target  and 
the  skin  is  16  inches — which  is,  however,  probably  greater  than  the 
average  distance  for  radiodontic  work — and  no  filter  is  used ;  do  not  ex- 
ceed what  I  shall  call  the  safe  dose  of  2400  milliampere-seconds  (4800 
milliampere-seconds  is  the  erythemia  dose,  recall). 

If  the  distance  is  only  about  8  inches  between  target  and  skin — 
which  perhaps  is  a  little  nearer  the  average  distance  for  radiodontic  work 
as  practiced — then  do  not  exceed  the  safe  dose  of  600  milliampere-seconds, 
unless  a  filter  of  one  millimeter  of  aluminum  is  used,  when  the  dose  may 
be  doubled,  that  is  made  1200  milliampere-seconds. 

If  a  full  safe  dose  is  given  wait  two  weeks  or  a  month  before  making 
any  further  exposure  and  so  guard  against  a  cumulative  effect. 

Making  radiographs  of  one  side  of  the  mouth  has,  of  course,  very 
little  effect  on  the  skin  of  the  other  side  of  the  face. 


THE  DANGER   OF  THE  X-RAYS  425 

Suppose  now  we  take  a  case  from  practice  and  see  how  a  man  would 
figure  his  dosage.  He  makes  measurements  and  finds  the  distance  from 
target  to  skin  to  be  12  inches.  The  safe  dose  at  8  inches  is  600  milliam- 
pere-seconds.  Apply  the  rule  now  that  the  dose  may  be  increased  directly 
with  the  square  of  the  distance.  The  square  of  12  is  144,  the  square  of  8 
is  64;  144  is  2^4  times  as  much  as  64.  Two  and  one-fourth  times  600 
milHampere-seconds  equals  1350  milhampere-seconds. 

Without  going  into  a  detailed  description  of  "  the 
^tif''i»^'^*'^  why  and  the  wherefore  "  of  the  fact,  it  may  simply 

be  stated  that  it  requires  a  greater  skin- dose  of 
X-rays  to  make  a  radiograph  with  a  very  small  X-ray  machine  than 
it  does  with  a  medium  or  large  machine.  Hence  the  number  of  radio- 
graphs which  can  be  made  with  safety  varies  somewhat  with  the  size  of 
the  X-ray  machine.  With  the  smaller  machines  fewer  radiographs  can 
be  made  without  exceeding  the  safe  dose. 

Men  with  small  machines  should  be  particularly  careful,  or  they 
will  exceed  the  safe  dose  and  may  produce  dermatitis.  Likewise  men 
who  employ  the  "  soft  tube  technic  "  must  remember  that  the  low  vacuum 
of  the  tube  necessitates  a  greater  millianpere-second  exposure.  Dr.  Geo. 
M.  MacKee*  reports  having  seen,  "  in  sixteen  months,  eight  cases  of 
radiodermatitis,"  i.e.,  X-ray  burn,  which  were  produced  incident  to 
radiographic  examination  of  the  teeth. 

Dentists  must  equip  themselves  with  the  right  kind  of  machine,  and 
they  must  know  how  and  must  keep  tab  on  their  dosage  if  they  expect 
to  do  much  radiographic  work.  It  is  dangerous  to  attempt  to  examine 
all  the  teeth  in  a  mouth  with  a  small  X-ray  machine,  then  follow  this  with 
re-examinations  as  canal  work  is  being  done,  unless  the  operator  keeps 
careful  track  of  the  dose  he  is  giving  and  stops  when  he  reaches  the  safe 
dose  limit. 

Many  dentists  who  are  doing  all  of  their  own  X-ray  work  should 
either  get  bigger  machines  and  use  them  more  intelligently  or  they  should 
refer  most  of  their  work  to  specialists  and  do  only  the  simpler,  easier 
work  themselves. 

As  long  as  the  fee  for  dental  radiographs  remained 
TnflMCnce  of  Tecs        high    the    probability    of    excessive    dosage    due    to 

the  making  of  many  radiographs  was  not  great. 
But,  as  more  of  the  work  is  being  done,  the  fee  is  getting  so  low 
in  many  localities  that  it  no  longer  offers  the  protection  it  once  afforded. 


*  Dental  Cosmos,  May,  1916. 


426  APPENDIX 

but  becomes  instead  the  chief  factor  in  the  development  of  careless,  dan- 
gerous practices. 

As  stated  in  Chapter  VIII  the  first  rule  regarding 
Ch^CkCtrlC  test  for      the  exposure  of  patients  is  not  to  expose  them  any 

longer  than  necessary.  Conscientious  and  consistent 
use  of  the  electric  test  for  pulp  vitality  will  cut  down  the  number  of  radio- 
graphic exposures  necessary,  especially  in  cases  where  the  entire  mouth 
is  to  be  examined  in  a  search  for  infection,  and  it  should  therefore  be 
used. 

In  the  past  the  writer  has  been  a  conscientious  advo- 

0arck$$llC$$  and        ^ate  of  the  belief  that  the  dentist  should  do  at  least 
Ignorance* 

a  part  of  his  own  radiographic  work.    But,  as  dentists 

commence  to  take  up  the  work  now,  I  am  appalled  at  the  degree  of  igno- 
rance and  carelessness  displayed.  Unless  I  can  see  some  evidence  of 
study  of  the  subject  before  long,  I  shall  be  forced  to  conclude  that  radio- 
dontic  work  should  be  done  only  by  a  few  men  who  have  the  ambition 
to  do  it  as  it  should  be  done. 

I  feel  safe  in  predicting  that,  unless  intelligence  is  soon  displayed 
by  dentists,  a  wave  of  disaster  from  X-ray  lesions  will  sweep  the  country, 
leaving  more  victims  than  was  claimed  by  the  X-rays  directly  after  they 
were  discovered.  These  victims  will  be  both  dentists  and  dentists'  patients, 
to  the  best  of  my  ability  to  judge,  mostly  the  former,  for  most  dentists 
seem  to  fail  utterly  to  appreciate  the  necessity  of  protecting  themselves. 

It  was  learned  from  disastrous  experience  that  the  operator  should 
have  protection.  Protection  was  accordingly  given  and  because  this  pro- 
tection has  proved  effective  the  tendency  among  even  the  best  X-ray  men 
seems  to  be  to  dispense  with  as  much  of  it  as  possible.  This  tendency  car- 
ried too  far  will  result  in  disaster.  There  is  every  reason  in  the  world 
why  the  operator  should  have  protection  and  practically  no  reason,  unless 
inertia  may  be  considered  a  reason,  why  he  should  not.  I  earnestly  advise 
the  use  of  the  lead  screen  or  cabinet  by  all  operators. 

Some  men  make  it  a  practice  to  hold  the  film  in  the  patients's  mouth 
during  its  exposure.  This  is  positively  unnecessary  and,  if  the  practice  is 
continued,  is  certain  to  result  in  injury  to  the  operator. 

Other  operators  have  their  assistant  hold  the  film  in  the  patient's 
mouth  during  exposure.  This  is  worse  than  for  the  operator  to  hold  it,  for 
it  is  less  fair  and  less  humane,  and  also  it  may  prove  to  be  very  expensive 
in  case  the  assistant  receives  a  burn  and  brings  suit  under  the  "  employer's 
liability  and  compensation  law  "  such  as  we  have  in  many  different  States. 

As  I  have  said  elsewhere,  properly  handled  the  X-rays  are  harmless, 


THE  DANGER   OF   THE  X-RAYS  427 

so  harmless  that  the  tendency  is  to  cease  handHng  them  properly  when 
they  may  become  woefully  harmful. 

n^-.u.*.  -nu...*  Since  the  effect  of  the  X-rays  varies  inversely  with 

roiitis  Jibout  ,  .   ,      , .  ...  -^ ,      . 

Protection  of  the  square  01  the  distance  it  is  quite  apparent  that  it 

Operator.  jg  advantageous,  as  a  means  of  protection,  for  the 

operator  to  be  as  far  away  as  possible  from  the  tube  while  it  is  in  opera- 
tion.    A  foot  switch  (Fig.  467)  or  any  other  form  of  extension  control 


Fig.  467,     A  foot-switch  by  means  of  which  the  operator  may  stand  any  desired  distance  from 
the   X-ray   machine   and   tube    when   the   current   is   turned   on. 

leading  from  the  machine  may  be  used  to  enable  the  operator  to  increase 
the  distance  between  himself  and  the  tube.  It  is  common  and  good  prac- 
tice to  have  the  X-ray  machine  controls  mounted  on  a  stand  back  of  the 
screen  or  on  the  back  of  the  l^ad  screen  (Fig.  468).  Wires  lead  from 
the  X-ray  machine  to  the  screen,  which  wires  may  be  made  of  any  desired 
length  and  so  the  operator  may  stand  as  far  away  from  his  tube  and 
machine  as  the  size  of  his  room  will  permit.  Also  the  controls  may  be 
mounted  on  the  X-ray  machines  and,  by  means  of  an  overhead  wiring 
system  (Fig.  361),  the  tube  removed  any  desired  distance  from  the 
machine. 

The  operator  should  not  only  make  it  a  rule  to  stand  as  far  away 
from  the  tube  as  possible  while  it  is  in  operation,  but  he  should  always 
see  to  it  that  the  active  hemisphere  of  the  tube  presents  away  from  him, 
and  incidentally  I  may  say  also  away  from  his  supplies  of  films  and 
plates. 

Figure  83  shows  a  protection  cover  for  the  top  of  lead  glass  bowls. 
I  wish  to  modify  the  remarks  on  page  278  referring 
Hlopecia.  to  the  possibility  of  baldness  being  produced  in  oper- 

ators due  to  the  continuous  small  dose  of  X-rays  they 
unavoidably  take. 

Recent  experiences  and  observations  lead  me  to  believe  that  X-ray 
operators  not  infrequently  lose  hair  due  to  the  action  of  the  X-rays. 


APPENDIX 


Fig.   468.      A   movable   pedestal   with    "  controls  "   mounted    on   it. 


THE  DANGER   OF  THE  X-RAYS 


429 


Figure  469A  shows  alopecia  in  a  patient  following  radiographic 
examination  of  the  frontal  sinuses  and  antra.  Figure  469B  is  the  same 
case  about  three  months  later  showing  a  new  growth  of  hair. 

I  know  so  little  of  the  history  of  this  case  I  shall  not  attempt  to  give 
it  further  than  to  say  that  there  was  never  any  dermatitis. 

I  shall  instead  give  the  history  of  a  similar  case  encountered  in  my 
own  practice ;  of  which  unfortunately  I  do  not  have  photographs.   Patient : 


Fig.  469A.  Case  of  alopecia  produced  in  ef- 
fort to  make  antero-posterior  radiograph  of 
the  antra. 


Fig.    469B.      Same   as   Fig.   469A  about   three 
months  later,  showing  new  growth  of  hair. 


Male,  age  30.  Blonde,  fine,  thin  hair.  Repeated  exposure  for  frontal 
sinus  examination  netting  a  dose  of  about  900  milliampere-seconds  in 
three  days,  distance  between  target  and  skin  about  9  inches,  no  filter  used. 
About  one  month  after  exposure  the  hair  commenced  to  come  out  of  the 
region  of  the  head  exposed,  continuing  to  come  out  for  about  two  months, 
at  the  end  of  which  time  the  head  was  quite  bald.  Almost  immediately 
then  the  hair  commenced  to  come  in  again  and  conditions  were  normal 
once  more  at  the  end  of  about  two  more  months.  There  was  never  any 
dermatitis. 

I  have  received  several  similar  histories  from  various  men.  In  one 
case  the  hair  commenced  to  fall  out  3  days  after  exposure  and  the  patient 
was  bald  in  about  10  days,  but  in  this  case,  as  well  as  all  others,  it  came 
back. 

The  tendency  is  to  say  that  "  the  hair  comes  back  thicker  than  ever," 
but  this  is  hardly  the  case.  However,  the  hair  does  come  back  as  thick 
as  ever. 

This  accident  of  producing  alopecia  for  a  young  lady  patient  would 
be  extremely  distressing  to  both  patient  and  operator.     I  advise  the  use 


430  APPENDIX 

of  a  filter  of  i  millimeter  of  aluminum  or  a  piece  of  sole  leather  for 
antrum  and  frontal  sinus  cases  to  guard  against  such  an  accident. 

Let  us  compare  the  currents  of  X-ray  machines  to  the 
r'i.55!!^^'!.5L^*         current  used  for  electrocution  and  so  get  some  idea 

of  the  danger  of  the  former.  J:*  or  electrocution  at 
the  Ohio  State  Penitentiary  the  current  used  is  60  cycle  A.  C,  voltage 
1700  to  2500,  amperage  4  to  6  for  one  minute. 

It  will  be  seen  from  this  that  the  current  of  X-ray  machines  is  never 
very  similar  to  the  electrocution  current.  The  current  of  the  primary 
is  higher  in  amperage  but  much  less  in  voltage ;  the  current  of  the  sec- 
ondary is  higher  in  voltage  but  much  lower  in  amperage. 

Of  course  one  should  avoid  coming  in  contact  with  the  wires  of 
either  the  primary  or  secondary  of  any  X-ray  machine,  for  the  shock 
may  be  either  painful  or  possibly  even  result  in  injury.  The  sensation 
when  receiving  a  considerable  quantity  of  electricty  is  that  of  a  "  jolt." 
The  "  jolt "  or  blow  may  knock  the  victim  down,  and  so  this  usually 
breaks  the  circuit,  but  if  it  should  knock  the  unfortunate  one  onto,  instead 
of  ofif  of,  the  "  live  "  wire,  the  injury  might  be  great. 

There  is  very  little  danger  of  receiving  a  shock  from  the  primary 
circuit,  but  both  the  operator  and  the  patient  sometimes  inadvertently 
come  in  contact  with  or  in  too  close  proximity  to  a  secondary  terminal. 
Contact  with  a  secondary  terminal  means  anything  from  an  unpleasant 
experience  to  a  disastrous  one,  depending  largely  on  the  size  of  the 
machine.  When  one  gets  very  close  to — within  one  or  two  inches — but 
does  not  come  in  contact,  with  a  secondary  terminal  a  spark  may  jump 
from  the  terminal.  This  is  of  course  unpleasant  and  may  cause  inflam- 
mation of  the  skin  at  the  point  of  entrance  of  the  spark.  See  Fig  102, 
which  illustrates  how  the  patient  may  be  protected  when  it  is  necessary 
to  bring  a  terminal  close  to  the  body. 


APPENDIX  TO  CHAPTER  X 

Stereoscopic  Kadiograpby. 

Some  improvement  in  dental  stereoradiographs  has  been  made  in  the 
past  five  years  but  the  full  possibilities  of  this  process  have  not  yet  been 
developed. 

The  idea  of  enlarging  dental  stereoradiographs  was  given  in  Chapter 
X,  Figs.  350  and  354.  In  pursuance  of  this  same  idea  it  is  the  writer's 
practice,  in  some  cases,  to  enlarge  stereoradiographs  as  in  Fig.  470.  The 
enlargement  is  made  on  a  plate — not  paper — and  observation  of  the 
stereoradiographs  is  made  with  a  stereoscope  like  the  one  illustrated  in 
Fig.  323.  The  result  is  sometimes  very  gratifying.  In  the  case  of  Fig.  470, 
for  example,  it  enabled  me  to  state  definitely  that  the  unerupted  cuspid 
lay  to  the  labial  of  the  lateral  incisor  root,  a  fact  which  I  had  failed 
to  determine,  to  my  complete  satisfaction,  by  ocular  and  digital  examina- 
tion of  the  mouth,  observation  of  single  radiographs,  and  observation  of 
unenlarged,  stereoradiographs. 

This  method  is  too  new  for  me  to  hazard  an  opinion  of  its  value,  but 
I  can  say  conservatively  that  it  seems  to  hold  the  greatest  possibilities 
of  any  method  thus  far  tried  by  me. 

The  technic  outlined  in   Chapter  X,  that  which  is 
tCCbttiC*  applicable    to    all    stereoscopic    work,    is    followed. 

The  film-holder,  Figs.  331,  332  and  333,  is  used,  if 
possible,  to  insure  placing  the  film  packets  in  the  mouth  in  the  same  posi- 
tion for  the  two  exposures.  If  the  film-holder  cannot  be  used  simply 
place  the  two  film  packets  in  the  same  position  to  the  best  of  your  ability 
to  do  it,  having  the  patient  hold  the  film  with  the  thumb  or  finger,  or  place 
the  film  in  the  mouth  as  in  Figs.  96  and  103.     (See  text  on  page  311.) 

Hold  the  head  immovable  by  using  a  device  similar  to  Fig.  no  or 
with  the  patient  in  a  sitting  posture  by  bandaging  the  head  to  the  head 
rest. 

Make  the  two  exposures,  shifting  the  tube  as  di- 
markiltd  ncgatiOCS.  rected  in  Chapter  X.  While  in  the  dark  room,  be- 
fore proceeding  with  development  mark  the  films 
right  (R),  and  left  (L),  the  operator  imagining  himself  in  the  position 
of  the  tube  at  the  time  of  exposure  and  that  one  exposure  has  been  made 
for  the  right  eye  and  the  other  for  the  left  eye.  Films  may  be  marked 
for  identification  by  placing  a  small  "  R  "  and  "  L  "  in  the  corner,  making 
the  mark  with  a  lead  pencil  (this  mark  can  be  seen  after  the  negative  is 
made)  or  by  punching  small  holes  in  the  corner  of  the  film  with  a  plate 
punch,  making  one  hole  for  the  right,  two  holes  for  the  left. 

431 


432 


APPENDIX 


Fig.   470.      Dental  radiograph  enlarged  for   observation   in   large  stereoscope. 


STEREOSCOPIC    RADIOGRAPHY 


433 


The  next  step  is  enlargement.  This  the  operator  may 
Gnlaraemcnt  have  done    for  him  by  any  photographer  or  he  may 

do  it  himself,  using  the  usual  photographic  enlarging 
apparatus,  which  consists  of  a  light  back  of  the  negative,  from  which  the 
enlargement  is  to  be  made,  shining  through  the  negative  and  an  enlarging 
lens  onto  a  standard  which  holds  the  photographic  plate  or  paper  (in 
this  case  a  plate)  on  which  the  enlargement  is  to  be  made.  (See  Figs. 
471  and  472.)  The  negative  to  be  enlarged  is  placed  with  the  coated  side 
away  from  the  source  of  light.    Enlarge  to  the  size  of  Fig.  470  or  larger. 


Fig.    471.      Enlarging   apparatus. 


^,       ,  -,         Observe    enlargements   by   means   of    a   stereoscope 

Observation  of  en-     ,.,     _.  v.      1  .li        1  i.  r        ^u 

largCd  StmoradiO-       like  Fig.  323.     By  placing  the  enlargement  from  the 
graphs*  right  negative  on  the  right  side  of  the  stereoscope, 

the  left  enlargement  on  the  left  side,  with  the  coated  sides  of  the  plates 
toward  the  light  of  the  illuminating  boxes,  the  operator  makes  his  ob- 
servation from  the  position  of  the  film  at  the  time  of  exposure.  By  re- 
versing the  negatives  as  they  are  placed  on  the  stereoscope — i.  e.,  by 
placing  the  right  enlargement  on  the  left  side  of  the  stereoscope  and  the 
left  enlargement  on  the  right  side  of  the  stereoscope,  with  the  coated  sides 
of  the  negatives  still  toward  the  light  of  the  illuminating  boxes,  or  by  re- 
versing the  negatives  so  their  sensitive  sides  present  away  from  the  light 
of  the  illuminating  boxes  toward  the  operator's  position  of  observation 
but  allowing  the  right  negative  to  remain  on  the  right  side  and  the  left 
on  the  left  side — the  position  from  which  the  operator  makes  his  obw 


434 


APPENDIX 


servation  is  changed  from  that  of  the  film  during  exposure  to  the  position 
of  the  X-ray  tube  during  exposure. 

The  foregoing  statements  regarding  the  mounting  of  negatives  on 
the  stereoscope  for  observation,  and  the  possibihties  of  changing  the 
operator's  position  of  observation  thereby  are  difficult  to  follow.  I  would, 
therefore,  advise  those  who  wish  to  take  up  this  work  to  make  test  or 
experimental  cases  by  stereoscopically  radiographing  the  hand  with  a  coin 


Fig.   472.      Enlarging   apparatus. 

on  it,  carrying  the  hand  radiographs  through  the  process  of  enlargement, 
and  then  observing  them  in  different  ways  in  the  stereoscope. 

As  I  have  stated  elsewhere  stereoscopic  work,  be- 

fl|)Dlicatlon  Of  tbC$C      cause  of  its  difficulty  will  remain  principally  in  the 
mctbods  to  Dentistry.  ■  v  ^       ^u  ^         ^       i  • 

hands  of  specialists,  ihe  practice  of  making  en- 
largements renders  dental  stereoscopic  radiography  a  definite  success 
in  cases  where  heretofore  it  has  been  a  failure.  Stereoscopic  work  remains 
too  expensive  to  come  into  general  use,  but  for  those  who  can  afford  it 
the  service  is  worth  the  fee  which  must  be  charged  for  it. 

I  have  heard  the  statement  made  repeatedly  that  the  two  negatives 
which  are  exposed  simultaneously  in  the  same  film  packet  can  be  mounted 
and  observed  with  a  stereoscope,  and  that  a  stereoscopic  effect  is  obtained. 
I  may  be  compelled  to  change  my  mind  sometime  but  right  now  I  may 


STEREOSCOPIC    RADIOGRAPHY 


435 


say  I  don't  believe  it.     At  least  /  cannot  observe  the  parts  perspectively 
with  such  negatives  and  I  am  inclined  to  think  that  the  imagination  of  the 


B^PLATE 


Fis.    473.       Drawing    wliich    shows    how    the    size    of    the    object    being    radioRraphed    may    be 
increased  by   moving   it  away   from   the  photographic  plate   toward   the   X-ray   tube. 


Fig.   474.      The    Ketcham    stereoscopic    film-holder. 

operator  is  responsible  for  any  stereoscopic  effect  obtained  from  such 
negatives. 


436  APPENDIX 

It  will  be  noticed  in  Fig.  351  that  the  coins  shown  are  of  slightly  dif- 
ferent sizes ;  they  are,  however,  all  of  the  same  denomination  and  so  the 
same  size.  The  reason  for  the  apparent  difference  in  size  is  illustrated 
diagrammatically  in  Fig.  473 ;  as  the  coin  is  moved  away  from  the  plate 
toward  the  target  the  shadow  of  it  cast  on  the  plate  gets  larger.  Fig.  474 
illustrates  the  Ketcham  film-holder  for  stereoscopic  work.  The  face 
is  marked  so  the  holder  may  be  removed  and  re-inserted  in  the  same 
position. 


CHAPTER  XI 

Cbe  Problem  of  Pulp  €anal  Surgery  and  Oral  Tnfectloti. 

Before  we  can  proceed  with  a  consideration  of  the 
Bad  0anal  morK.        problem  of  pulp  canal  work,  we  must  agree  that  there 

is  such  a  thing  as  "  bad  canal  work  " — i.  e.,  canal 
work  which  fails  to  eradicate,  or  prevent,  the  formation  of  local  foci  of 
infection  at  the  apices  of  the  roots  of  the  teeth.  In  fact,  most  canal  work 
is  of  this  kind.  I  state  this  dispassionately  as  a  fact,  not  with  the 
spirit  of  reprimand  and,  I  would  have  you  know,  I  do  not  believe  "  the 
canal  work  of  the  dental  profession  is  a  disgrace."  It  may  be  a  mistake 
but  it  is  not  a  disgrace.  Muriel  Strode  says,  "  It  is  no  disgrace  to  wear 
rags ;  the  disgrace  lies  in  continuing  to  wear  them."  Likewise,  it  is  no 
disgrace  to  make  a  mistake ;  the  disgrace  lies  in  continuing  to  make  the 
same  mistake. 

If  there  is  any  one  who  still  believes  that  it  has  been 

Tailure  to  Till  Canals      the  practice  of  dentists,  in  the  past,  to  fill  canals, 

^jjilj^  even  large  canals,  to  the  end  of  the  root,  look  at  Fig. 

475.  The  radiographs  shown  in  this  illustration 
were  obtained  by  giving  an  office  assistant  in  a  radiodontist's  office  these 
instructions :  "  Go  through  the  H's  in-  the  little  file  of  old  negatives  and 
select  all  the  cases  showing  canal  fillings  in  any  teeth  except  molars." 

Figure  475  shows  forty-eight  teeth  (none  of  them  molars)  in  which 
there  has  been  an  effort  made  to  fill  the  canals.  Forty-seven  are  failures 
so  far  as  success  in  reaching  the  end  of  the  roots  is  concerned  and  most 
of  them  show  evidence  of  osseous  infection  at  the  apices.  One,  an  upper 
first  bicuspid,  filled  recently  under  the  writer's  directions,  shows  the  canal 
fillings  encapsulating  the  ends  of  the  roots,  and  so  we  shall  call  this  a 
success  from  a  mechanical  standpoint  at  least. 

It  is  a  fact  then  that  it  has  not  been  the  practice  of 

KadiOflrapbS  dentists  to  fill  the  canals  even  of  anterior  teeth  and 

Canals  Of  tectb.         biscupids.    We   need   not   consider  the   question   of 

whether  or  not  it  is  possible  to  "  fill  the  canals  of  all 

molars  to  the  ends  of  the  roots  "  just  now.    Let  us  stick  to  the  problem  of 

filling  the  larger  canals  of  teeth  other  than  molars.    No  one  will  deny  the 

437 


43S 


APPENDIX 


Fig.   475.      Forty-eight   teeth,    other   than   molars,    where   efforts   have   been   made   to   fill    canals. 

The  canal  filling  material  fails  to  reach  the  end  of  the  root  in  forty-seven  out  of  the  forty-eight. 

These  teeth  were  selected  at  random. 


CANAL   SURGERY   AND    ORAL   INFECTION  439 

physical  possibility  of  filling  the  canals  of  the  teeth  referred  to  above — 
except  in  a  very  few  anomalous  cases — and  no  one  who  has  observed  a 
considerable  number  of  radiographs,  will  deny  the  fact  that  it  has  not 
been  done,  and  no  one,  who  has  commenced  to  "  check  up  "  his  root  canal 
fillings  with  radiographs,  will  deny  the  additional  fact  that  the  canals  of 


Figs.   476,   477   and  478.      Repeated  efforts  to   fill   the   canal   of   an   upper   central   incisor.      Note 
the  little  canal  leaving  the  main  canal,  to  the  mesial,  at  riglit  angles,   in  Figs.   477  and  478. 

teeth  never  will  be  filled  until  radiographs  are  used  to  show  the  operator 
when  he  succeeds  in  placing  his  canal  filling  to  the  end  of  the  root  and 
when  he  fails. 

One  of  my  friends  says  :  "  The  great  trouble  in  filling 
fft'rfll  raiiaU  canals    arises    from    the    fact    that   the    canal    filling 

material  doesn't  go  where  you  put  it."  And  so  it 
seems,  indeed,  when  one  commences  to  radiograph  his  canal  fillings. 
You  will  place  a  canal  filling  in  a  single-rooted  tooth  and,  before  radio- 
graphic examination  be  willing  to  swear  you  have  placed  it  to  the  end  of 
the  root,  only  to  learn,  after  radiographic  examination,  that  you  have  not. 
Figures  476,  477  and  478  illustrate  repeated  efforts  to  fill  the  canal  of 
a  central  incisor.  This  was  done  by  an  operator  of  unquestionable  ability. 
Figure  476  illustrates  the  result  of  the  first  effort.  The  second  effort  is 
not  illustrated — it  had  the  same  appearance  as  Figure  476.  Figure  477 
illustrates  the  result  of  the  third  effort.  Note  that,  even  though  the 
operator  is  using  force  enough  to  send  his  canal  filling  material  off  into 
a  canal  which  leaves  the  main  canal  almost  at  right  angles  to  the  mesial, 
still  the  main  canal  is  not  filled  to  its  end.  Figure  478  illustrates  the 
fourth  and  successful  effort  to  fill  the  canal  to  the  end. 


440  APPENDIX 

Let  us  not  waste  time  blaming  anybody  for  what  we 
andll^iu  "°^  ^^^^  ^^^  canal  work,   for  nobody  is  to  blame. 

The  only  men  who  deserve  condemnation  for  the 
work  they  have  done  in  the  past  are  those  who  have  made  no  effort  to 
fill  canals.  Until  recently  canal  work  was  considered  successful,  by 
dentists,  physicians,  scientists  and  the  public,  if  it  prevented  subsequent 
toothache,  and,  measured  by  this  standard,  the  canal  work  of  the  dental 
profession  has  been  a  success  But  the  extensive  use  of  the  radiograph 
and  the  theory  of  mestatic  infection  set  a  new  standard:  Pulp  canal 
work  must  not  only  prevent  subsequent  toothache,  it  must  also  prevent 
subsequent  periapical  infection.  Methods  which  fulfill  the  requirements 
of  the  old  standard  fail  to  meet  those  of  the  new,  so  they  must  be  dis- 
carded and  replaced  by  methods  which  do  eradicate  and  prevent  the 
development  of  foci  of  infection. 

The  answer  to  the  question :  "  What  shall  we  do  about  our  canal 
work?  "  is,  we  shall  do  better  canal  work  and  we  shall  do  less  canal  work. 
We  must  practice  the  sort  of  canal  work  advocated  by  Callahan,  Otto- 
lengui,  Rhein,  Best,  Biddle  and  other  leaders  in  this  work.  But  before 
we  can  adopt  what  we  know  to  be  the  best  methods  in  canal  work  we 
must  educate  the  public  to  the  point  where  they  will  readily  permit  us  to 
practice  such  methods,  and  as  we  do  this  we  will  incidentally  educate 
people  to  co-operate  with  us  to  prevent  the  necessity  of  canal  work.  Even 
the  best  methods  in  canal  work  can  be  and  will  be  improved  upon,  but 
just  at  this  time  it  is  not  common  for  dentists  to  make  a  practical  appli- 
cation of  the  knowledge  we  already  have  on  this  subject. 

I  refrain,  then,  just  now,  from  a  consideration  of  the  technic  of  better 
canal  work,  recognizing  the  fact  that  it  has  already  been  given  to  the  pro- 
fession time  and  time  again,  but  it  has  not  been  accepted  because  economic 
conditions  have  made  its  acceptance  impossible. 

The  average  dentist  today  occupies  a  rather  difiicult 
Hocraac  ricntist  position.     As  Dr.  Harry  Carr  facetiously  expresses 

it,  "  If  he  does  his  canal  work  as  he  has  been  doing 
it,  he  gives  his  patients  heart  trouble.  If  he  takes  the  time  necessary, 
and  does  it  as  he  now  believes  it  should  be  done  he  gives  them  heart 
failure — when  he  presents  his  bill."  This  is  funny  because  it  is  so 
pathetically  true.  Fees  for  canal  work  which  has  for  its  aim  only  the 
prevention  of  further  toothache  are  only  about  one-fifth  the  amount  which 
must  be  charged  for  canal  work  which  is  calculated  to  prevent  subsequent 
periapical  infection.  Yet  the  fact  remains,  the  more  expensive  methods 
must  be  adopted  and  practiced  by  all  ethical  dentists. 


CANAL   SURGERY  AND    ORAL  INFECTION  441 

"  But  how  ?  "  cries  the  average  dentist.  "  I  cannot  do  this  work 
unless  I  am  paid  for  it,  and  my  patients  either  will  not  or  cannot  pay  me." 

The  patient  who  could  but  will  not  pay  for  good  canal  work  gives  me 
little  concern.  Such  a  patient  is  either  impervious  to  reason  or  he  or  she 
has  not  had  the  matter  presented  in  the  proper  light. 

But  patients  who  actually  cannot  afford  the  work  (and  there  are 
thousands  upon  thousands  of  them)  do  give  me  much  concern.  Many 
people  cannot  afford  good  canal  work  because  they  need  so  much  of  it. 
If  they  had  less  of  it  to  be  done  they  could  afford  it.  And,  note  this : 
it  is  important.  Canal  work  becomes  necessary  when  a  tooth  aches,  and 
most  toothache  is  preventable. 


And  so  we  arrive  where  every  thinking  man  arrives 
^^Cca^^Us*^'"^  ^^  ^^  gives  this  problem  of  canal  work  sufficient  con- 
sideration. We  see  that  something  must  be  done  to 
prevent  conditions  which  necessitate  canal  operations.  We  arrive  at  this 
conclusion  if  we  consider  the  problem  from  a  financial  aspect,  as  I  have 
just  considered  it;  we  arrive  at  this  same  conclusion  if  we  consider  the 
disasters  of  poor  canal  work  or  the  difficulties  or  shortcomings  of  the 
best  canal  work ;  and  we  arrive  at  this  same  conclusion  if  we  consider  the 
unnecessary  pain  suffered  and  the  waste  of  time  and  energy. 

Something  must  be  done  to  prevent  conditions  which  necessitate  canal 
work.  That  is,  something  must  be  done  to  stop  the  practice,  common  with 
most  people,  of  deliberately  allowing  their  teeth  to  ache  before  patronizing 
a  dentist,  instead  of  visiting  him  periodically  and  allowing  him  to  fill  and 
refill  their  teeth  as  soon  as  cavities  appear  and  so  prevent  the  occurrence 
of  toothache  and  the  necessity  of  canal  operations.  Figure  479  illustrates 
this  idea  of  pulp  conservation  and  prevention  of  toothache. 

The  thing  which  must  be  done  is  to  educate  the  people  to  a  better 
understanding  of  the  folly  of  allowing  their  teeth  to  ache. 

It  would  take  years  to  accomplish  this  by  lectures,  tracts,  magazine 
articles,  newspaper  articles,  and  personal  advice.  But  it  can  be  accom- 
plished in  twenty-four  months  by  a  publicity  campaign  conducted  by  the 
National  Dental  Association, 


Since  we  contemplate  educating  the  public  it  might 

6dMStk>n'flJ»0CateS      ^^  ^^^^^  ^°  ^^°P  ^""^  consider  some  of  the  character- 
istics of  our  prospective  student  that  our  efforts  at 
teaching  may  be  governed  accordingly.     The  public  is  a  big  lazy,  indif- 
ferent duffer,  unwilling  to  learn  anything.     To  teach  him,  you  must 


442 


APPENDIX 


Canes 
(UGcay^ 


J^estorat/On 


Canes 


li'estorat/oti        A/gw  J^ostorat/on 


Pulp 


From 

Where  Puljo  Has  f^&cedGcf 


/^GStorat/o/7 


Canes 


/\ge  Of 
Patient 
/O  Years 


/ige  Of 
^  Patient 
30  Years 


\  ^at/erit 
35  Years 
Note  the 
r/7J/ng/\io\^ 

^EntGrsThat 

)PartofThoth 
Where  Pu/p 
Used  to  be. 
But  Has 

j  F^eceded. 


Prom  Where 
Pulp  Has 
I^ecec/Gd 


A/ew  ^Restoration 
Enters  Tooth  to 
GreatDGpth  Without 
I^each/ng  Pulp. 


Fig.   479.      A  schematic  drawing  to  show  how  teeth  may  be  taken  care  of  in  such  a  way  as  to 
avoid  the   necessity  of  pulp  canal   work.      (Drawing  by  W.   O.   Godwin,   junior   dental   student, 

1917.) 


CANAL   SURGERY  AND    ORAL   INFECTION  443 

amuse  him,  arouse  his  curiosity,  scare  him,  or  make  the  lesson  so  easy 
that  it  can  be  learned  without  effort.  It  should  be  borne  in  mind,  also, 
that  the  public  has  a  thousand  or  so  other  teachers  besides  us  annoying 
him.  The  socialist  wishes  to  educate  him  to  save  him  from  capitalism ; 
the  capitalist  wishes  to  educate  him  to  save  him  from  socialism ;  the 
minister  wishes  to  educate  him  in  right  conduct  to  save  his  soul ;  the 
physical  culturist  wishes  to  educate  him  to  save  him  from  physical  deterio- 
ration ;  the  sex  hygienist  wishes  to  educate  him  to  save  him  from  syphilis 
and  gonorrhea,  and  so  on  and  on.  No  wonder  he  is  lazy  and  indifferent 
He  has  to  be  in  self-defense. 

If  you  accept  my  picture  of  the  public  as  a  student,  as  I  have  drawn 
it,  you  will  agree  with  me  that  it  is  useless  to  attempt  to  teach  him  a  long 
lesson.     It  would  be  futile  to  attempt  to  teach  him  this,  for  example : 

"  Toothache  can  be  avoided. 

"  It  can  be  avoided  if  you  will  visit  your  dentist  at  regular  intervals 
and  have  him  fill  and  refill  your  teeth  as  soon  as  cavities  occur. 

"  You  should  avoid  toothache. 

"  Because,  to  commence  with,  who  wants  to  suffer  with  the  tooth- 
ache, anyhow  ? 

"  Because  a  tooth  which  has  ached  must  be  treated. 

"  Because  the  treatment  of  teeth  takes  much  of  your  time,  and  your 
time  is  valuable. 

"  Because  the  treatment  of  teeth  by  modern  methods  is  very  expen- 
sive. (In  fact,  toothache  and  the  treatment  it  necessitates  is  a  luxury  to 
be  indulged  in  to  any  great  extent  only  by  the  well-to-do.) 

"  Because  once  a  tooth  is  allowed  to  ache,  there  is  the  chance  that 
you  may  lose  it,  and  you  need  all  the  teeth  you  have. 

"  And  because,  unless  a  tooth  which  has  once  ached  is  properly 
treated,  it  may  later  ruin  your  health  and  life  by  causing  rheumatism, 
heart  trouble,  gastric  ulcer  and  other  serious  diseases. 

"So 

"  You  mustn't  let  your  teeth  ache." 

I  would  like  to  teach  all  of  the  foregoing  to  the  public,  and,  if  I  could, 
it  would  be  the  nearest  thing  to  a  solution  of  the  problem  of  canal  work 
we  have  ever  had.  But  it  is  impossible  to  teach  so  much,  and  fortunately 
it  is  not  necessary.  A  small  part  of  the  public  will  demand  the  lesson 
in  full  as  I  have  just  given  it,  even  asking  for  further  elaboration,  and 
we  can  give  it  to  them,  but  for  the  big,  big  public  as  a  whole,  the  lesson 
must  be  shorter,  very  much  shorter.  Something  like  the  lessons  taught 
by  the  big  commercial  advertisers,  such  as  "  He  Hears  His  Master's 
Voice,"  "  Eventually,  Why  Not  Now  ?  "  "  There's  a  Reason,"  and  others. 


444 


APPENDIX 


In  the  practice  of  radiodontia  I  have  this  problem  of  canal  work 
brought  constantly  before  me  and  I  have  given  much  thought  to  the  selec- 
tion of  something  sufficiently  short  to  reach  the  public  and  yet  capable 
of  accomphshing  the  purpose  I  wish  it  to  accompHsh. 

I  suggest  Fig.  480  as  an  official  slogan  for  the  National  Dental  Asso- 
ciation, to  be  used  on  bill-boards,  street-car  cards,  advertising  spaces  in 
the  magazines,  on  the  handles  of  tooth-brushes,  on  tubes  containing  tooth 
pastes,  anywhere  and  everywhere  where  people  will  see  it. 


Fig.  480.     Suggested  as  an  official  slogan  for  the  National  Dental  Association. 


Aside  from  the  advantage  of  brevity,  this  has  the  further  advantage 
of  arousing  the  curiosity.  When  first  read  it  sounds  rather  nonsensical, 
and  so  gets  a  second  thought  from  the  reader.  It  allows  one  who  reads 
it  to  become  facetious  with  himself  and  remark  to  himself :  "  Fine  advice, 
that.  I  wonder  who  thinks  I  have  toothache  just  for  spite."  And  its 
greatest  advantage  is,  it  can  be  rewiemhered.  Even  that  part  of  the  public 
which  demands  its  dentists  to  give  it  the  lesson  in  full  will  forget  most 
of  the  lesson  and  remember  only  that  there  are  good  reasons  why  you 
should  not  let  your  teeth  ache. 

The  situation  now  is  that  no  person  feels  any  especial  pang  of  regret 
and  remorse  when  they  "  suddenly  " — after  a  few  years  of  neglect — 
develop  toothache.  And  why  should  they?  The  attitude,  if  not  the 
teaching,  of  the  dental  profession  has  been :  "  Ah,  Mr.  Citizen,  you  have 
the  toothache!  Well,  that  doesn't  make  any  particular  difference.  I  can 
fix  that  in  a  jiffy  for  ninety-eight  cents." 


CANAL   SURGERY  AND    ORAL   INFECTION  445 

Even  though  you  see  the  necessity  for  pubHcity  work 

flaloca^^rpSS  ^^  ^  ^^^  '^'  ^"^  ^""^  therefore  in  favor  of  it,  you  may, 
nevertheless,  think  that  I  am  wanting  the  National 
Dental  Association  to  do  something  it  cannot  do.  Let  us  see  if  I  am 
in  the  habit  of  asking  for  impossible  things.  What  is  my  attitude  toward 
dentists  who,  in  my  mind,  stand  convicted  of  doing  bad  canal  work?  I 
do  not  say  to  them :  "  You  must  adopt  more  modern  and  expensive 
methods  of  treatment  forthwith,  and  that's  all  there  is  to  it,"  for  I  know 
that  the  great  amount  of  canal  work  to  be  done  makes  this  an  economic 
impossibility.  Neither  do  I  ask  the  National  Dental  Association  to  do 
something  which  is  economically  impossible.  What  I  want  it  to  do,  it 
can  do.  It  can  do  the  publicity  work  I  suggest,  and  it  must.  We  owe  it 
to  humanity  and  ourselves. 

The  man  who  thinks  this  campaign  is  a  financial  impossibility  has 
not  given  this  matter  sufficient  consideration.  We  wish  to  do  two  things : 
We  wish  to  cause  the  people  to  ask  the  meaning  of  the  You-Mustn't-Let- 
Your-Teeth-Ache  slogan  and  we  wish  to  have  dentists  prepared  to  answer 
inquiries  regarding  it. 

The  profession  of  dentistry  could  not,  it  is  my  opinion,  raise  enough 
money  to  get  the  You-Mustn't-Let-Your-Teeth-Ache  slogan  to  the  people. 
But  there  is  a  way  to  get  this  slogan  before  the  people  without  spending  a 
fortune :  The  manufacturers  of  dentifrices  and  tooth-brushes  spend  mil- 
lions of  dollars  annually  for  advertising.  Most  of  them  would  be  glad 
to  use  the  slogan  I  have  suggested  in  a  corner  of  all  of  their  advertise- 
ments if  they  were  asked  to  do  so  by  the  National  Dental  Association, 
and  if  they  understood  the  humane  object  of  this  campaign.  It  is  a  tre- 
mendous and  pitiful  mistake  for  any  one  class  of  men  to  think  they  are 
any  better  than  another  class,  and  dentists  who  think  manufacturers  are 
not  interested  in  the  welfare  of  humanity  are  "  dead  wrong."  Forsythe 
and  Eastman  are  manufacturers  you  know.  So  much  for  the  problem 
of  reaching  the  people. 

The  problem  of  preparing  dentists  to  promote  the 
educating  Dentists.  education  of  the  public  started  by  a  Never-Let-Your 

Teeth-Ache  campaign  can  be  handled  in  a  most  inex- 
pensive way.  The  pages  of  our  dental  magazines  are  always  at  our  dis- 
posal and  the  owners  of  these  magazines  have  always  done  their  share, 
or  more  than  their  share,  to  support  such  enterprises  as  the  one  under 
consideration. 

I  would  not  have  you  think  that  I  am  obsessed  with  the  delusion  that 
it  will  take  no  money  at  all  to  conduct  an  educational  campaign  such  as 


446  APPENDIX 

I  have  outlined,  for  of  course  it  will.  But  it  will  not  take  "  bushels  of 
it  " ;  it  will  not  take  any  more  than  can  be  raised  with  ease ;  for  there 
are  thousands  of  dentists  who  are  more  than  willing  to  contribute ;  they 
want  to  contribute  to  such  a  cause. 

It  is  not  impossible,  but  it  is  not  probable  either,  that 
Ttl  the  meantime*  the  publicity  campaign  outlined  in  the  preceding 
pages  will  be  developed.  If  it  is  never  developed,  or 
until  it  is  developed,  or  while  it  is  developing,  I  advise  dentists  who  desire 
to  practice  good  canal  work  to  avail  themselves  of  the  help  afforded  in 
Figures  481A  to  486.  Explain  one  or  two  or  all  of  these  plates  to  patients 
and  you  will  gain  a  more  intelligent  co-operation  than  you  have  hitherto 
found  it  possible  to  get. 

Before  dental  radiographs  were  used  the  dentist  who  wished  to 
explain  canal  work  and  abscess  formation  to  his  patients  was  compelled 
to  use  drawings  and  models  for  the  purpose.  A  drawing  or  a  model  does 
not  make  the  same  impression  produced  by  a  radiograph,  because  a 
drawing  of  an  abscess  is  anybody's  and  everybody's  abscess.  Somebody 
has  said  something  like  this :  "  Everybody's  work  is  nobody's  work." 
Likewise  everybody's  abscess  is  nobody's  abscess ;  nobody  will  own  it. 
But  an  abscess  in  a  radiograph  is  some  particular  individual's  abscess ;  it 
belongs  solely  and  personally  to  Mrs.  Jones,  Mrs.  Smith  or  Mr.  Hancock, 
which  makes  a  world  of  difference. 

Figures  481 A  to  486  illustrate  how  the  X-rays  may  be  used  to  advan- 
tage in  educational  work.  A  careful  study  of  these  plates  will  prove 
illuminative  to  most  dentists  and,  as  an  aid  to  dentists  in  explaining  to 
patients  the  difference  between  good  canal  work  and  no  canal  work,  or 
poor  canal  work,  they  should  prove  to  be  of  the  utmost  value.  Indeed 
they  seem  to  me  to  be,  at  present,  the  answer  for  the  men  who  wish  to 
practice  good  canal  work,  but  have  been  unable  to  gain  the  co-operation 
of  their  patients. 

«i....i,i  er^^^x  «iK«*      There    has    been    much    discussion    recently    as    to 
material  encapsulate     whether  canal  fillmg  material  should  just  reach  the 
^^^'  end  of  the  root  or  pass  through  it  and  encapsulate 

the  end.  I  leave  it  a  more  or  less  open  question  as  to  which  is  preferable, 
believing  myself,  however,  the  ideal  filling  is  one  which  just  reaches  the 
end  of  the  canal,  filling  all  apical  foramina,  but  not  passing  through  into 
the  periapical  space.  While  it  is  my  opinion  that  such  a  canal  filling  is 
the  ideal  one,  it  is  my  further  opinion  that  this  ideal  cannot,  as  a  rule,  be 
realized,   for,  no  matter  how  many  radiographs  are  made  at  different 


CANAL   SURGERY  AND    ORAL   INFECTION  447 

stages  of  the  work,  the  fact  remains  that  just  at  the  time  the  operator  is 
engaged  in  the  work  of  filling  the  canal,  he  is  working  in  the  dark  and  in 
order  to  get  the  canal  fiUing  to  the  end  of  the  root,  he  will  usually  force 
a  little  through.  As  has  been  pointed  out  in  the  Appendix  to  Chapter 
VI  it  is  sometimes  impossible,  in  upper  biscupids  and  lower  molars  par- 
ticularly, to  determine  from  radiographs  whether  a  canal  filling  reaches 
the  apex  or  not,  unless  a  little  passes  through  appearing  as  a  little  button 
or  cap  at  the  root  end. 

Canal  filling  material  which  passes  through  the  root  in  a  soft  condi- 
tion and  "  mushes  "  out  over  the  root  end  seems  to  cause  no  irritation.  A 
gutta  percha  point  protruding  through  the  apex,  however,  is  more  likely 
to  produce  irritation,  pain  and  suppuration. 

It  is  very  unfortunate,  but  it  is  very  true,  that  we  are  much  more 
likely  to  have  post-operative  pain  if  we  fill  canals  just  to  or  just  through 
the  end  of  the  root  than  we  are  when  the  canal  filling  fails  to  reach  the 
end.  It  is  very  discouraging  for  the  conscientious  dentist  to  lose  his 
patients  because  he  has  filled  canals  well  and  there  has  been  pain  follow- 
ing the  operation.  He  knows  he  might  have  avoided  the  production  of 
the  pain  by  being  less  thorough.  If  he  has  forced  a  little  filling  material 
through  the  end  of  the  root,  it  is  not  unlikely  that  he  will  be  condemned 
by  both  the  patient  and  the  patient's  physician.  He  very  probably  has 
received  a  fee  which  looked  large  to  the  patient  but  which,  considering 
the  time  he  spent  on  the  case,  is  less  than  other  dentists  are  charging  who 
do  not  fill  canals  but  whose  patients  do  not  suffer  after  the  operation. 

Pain  after  canal  filling  should  be  controlled  in  many  cases  by  the  use 
of  some  anodyne,  such  as  an  aspirin-codein  mixture. 
For  example 

3>   Acetylsalicylic  acid  grs.  xxx 
Codein  sulphate        grs.  ii. 
M.    Ft.  Caps.  No.  xii. 
Sig.    If  in  pain  take  one  capsule.     Repeat  in  thirty 
minutes  if  necessary.     Thereafter  every  two  hours  if 
in  pain. 
Filling  material  through  the  root  end  of  a  lower  molar  may  pass  in 
the  inferior  dental  canal  and  encroach  on  the  inferior  dental  nerve  when 
the  pain  is  very  great  and  extraction  of  the  tooth  may  be  necessary. 

At  a  dental  meeting  recently  a  man  asked  me,  "  Is 
Ulbat  i$  a  Bad  ^  mechanically  imperfect  canal  filling  necessarily  a 

Canal Tillmg.         ^u  a^         1  ^u-     ?" 
bad     canal  fillmg? 

Look  at  Figure  487.  To  the  best  of  our  ability  to  judge,  dental 
abscesses  produce  diseases  like  this,  and  imperfect  canal  fillings  produce 


448 


APPENDIX 


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CANAL    SURGERY   AND    ORAL    INFECTION  449 


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CANAL    SURGERY    AND    ORAL    INFECTION  451 


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CANAL   SURGERY   AND    ORAL   INFECTION  453 


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CANAL   SURGERY  AND    ORAL   INFECTION 


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456 


APPENDIX 


dental  abscesses.  So  mechanically  imperfect  canal  fillings  are  "  bad  " 
canal  fillings,  aren't  they?  Even  mechanically  perfect  canal  fillings  may, 
under  certain  conditions,  be  very  undesirable  things  to  have  in  the  mouth, 


Fig.    487.      Case    of    arthritis   deformans.      To 
the    best    of    our    ability    to    judge,    oral 
infection     causes     diseases     like     this. 
(By  courtesy   of  the  Dental  Digest.) 


Fig.  488.      Case  of  arthritis  deformans  caused 

by   oral   infection. 
(Courtesy   of   Dr.    Thomas   B.    Hartzell.) 


for  a  canal  filling  may  be  mechanically  perfect  without  being  perfect  from 
a  surgical — i.  e.,  a  bacteriological — standpoint  and  such  a  canal  filling  is 
certainly  "  bad." 

Any  sort  of  canal  filling  then,  and  certainly  mechanically  imperfect 
canal  fillings,  worry  the  conscientious  dentist  and  physician  when  they 
are  in  the  mouths  of  patients  who  are  seriously  ill  with  any  disease  which 
might  possibly  be  produced  by  some  focus  of  infection. 

Through  the  courtesy  of  Dr.  Thomas  B.  Hartzell  I  am  able  to  print 
Figure  488.  Here  is  a  man  with  arthritis  deformans  caused,  to  the  best 
of  the  ability  of  those  in  charge  of  the  case  to  judge,  by  dental  infection. 
Think  of  this  for  a  moment,  then  answer  the  question :  Shall  we  continue 
to  allow  people  to  lay  themselves  liable  to  diseases  like  this,  or  shall  we  do 
"  less  and  better  canal  work?  " 

Case:  One  of  arthritis,  neuritis,  malnutrition.     Man 

Hnd^a  tSon^  ^^^  "°^  ^^^"  ^^^^  *°  ^°^^  ^°^  weeks.     Referred  to 

radiodontist  by   physician.      Radiographic   examina- 
tion revealed  dento-alveolar  abscesses  and  much  loss  of  osseous  tissue, 


CANAL   SURGERY   AND    ORAL   INFECTION 


457 


due  to  pyorrhea.  The  affected  teeth  were  extracted.  The  patient's  con- 
dition improved  promptly  and  continued  to  improve  for  several  weeks. 
An  upper  anterior  bridge  was  made,  using  the  two  cuspids  for  abutments. 
The  Thursday  before  the  Monday  when  the  patient  had  arranged  to  go  to 
work  again,  he  suffered  a  relapse  and  developed  pain  in  the  region  of 
one  of  the  abutment  cuspids.  His  physician  again  sent  him  to  the  radio- 
dontist.  A  radiograph  was  made  of  the  tooth  causing  pain.  It  showed 
the  canal  filling  reaching  only  about  two-thirds  the  distance  to  the  apex 


Fig.  489.      Radiographs  of  hands  of  Fig.   4SS. 

of  the  root,  and  tissue  changes  indicative  of  abscess  formation  in  the 
periapical  region.  The  bridge  was  removed,  also  the  imperfect  canal 
filling.  The  periapical  tissues  were  disinfected  by  pumping  a  four  per 
cent  solution  tincture  of  iodin  in  water  through  the  root.  Again  the  man's 
general  physical  condition  began  to  improve,  and  continued  to  improve 
while  the  canal  work  in  his  mouth  was  done  over  again,  this  time  checking 
the  work  with  radiographs. 

From  the  foregoing  it  will  be  seen  that  the  time  is  already  here  when 
city  dentists,  at  least  (when  this  condition  of  affairs  will  prevail  in  the 
smaller  town  I  do  not  attempt  to  say)  must  see  to  it  that  they  fill  canals. 
A  man  may  practice  septic  canal  work  and  not  be  caught  at  it,  but  if  he 
places  a  mechanically  imperfect  canal  filling  in  a  tooth  any  one  who  looks 
at  a  radiograph  of  it  can  see  his  failure. 


458  APPENDIX 

In  the  case  just  referred  to  the  patient  had  paid  seventy-five  dollars 
for  the  bridge.  Seventy-five  dollars  fastened  to  failures  in  canal  work — 
failures  zvhich  might  have  been  avoided  had  radiographs  been  used  to 
"  verify  "  the  canal  fillings. 

I  question  the  necessity  of  always  making  a  number  of  radiographs 
of  single-rooted  teeth  to  insure  insertion  of  the  canal  filling  to  the  end 
of  the  root.  A  radiograph  before  the  tooth  is  opened,  another  with  a 
wire  reaching  the  end  of  the  root  and  a  third  when  the  canal  is  filled, 
certainly  cannot  be  considered  bad  practice,  but  I  repeat,  I  question  the 
necessity  of  any  save  the  radiograph  after  the  canal  has  been  filled  in  the 
average,  non-septic,  single-rooted-tooth  case. 

And  now  we  come  to  a  consideration  of  the  filling 
Jli!!2.ir5^?]£  of  the  canals  of  molar  teeth.     Some  dentists  seem  to 

molar  vcetn.  ,  •  ,    ,      ...          ., ,        ^,,    ,  ,      r 

thmk  that  it  is  impossible  to  fill  the  canals  of  any 
molar  tooth  to  the  apices  of  the  roots.  They  are  wrong.  Other  dentists 
seem  to  think  that  it  is  possible  to  fill  the  canals  of  all  molar  teeth  to  the 
apices  of  the  roots.    They,  too,  are  wrong. 

Figure  490  is  a  radiograph  of  the  results  of  an  assignment  in  technic 
for  the  Junior  class  (1916)  at  the  Indiana  Dental  College.  The  assign- 
ment was  that  each  student  should  open  the  canals  of  a  dissociated 
molar  through  the  ends  of  the  roots,  then  fill  the  canals  by  the  Callahan 
method.  The  following  table  (page  459 ")  is  a  record  of  the  results  of  this 
assignment. 

A  study  of  the  table  given  will  reveal  the  following  pertinent  facts : 

Number  of  molar  teeth,  the  canals  of  which  were  filled:  61. 

Number  of  teeth  used  for  this  work :  225. 

Thus  the  average  is  that  over  three  teeth  were  used  before  the  student 
succeeded  in  opening  the  canals  of  one. 

Total  time  devoted  to  the  teeth  where  efforts  to  open  the  canals  met 
with  failure:  185  hours  55  minutes. 

Entire  length  of  time  consumed  in  the  work  of  opening  canals  of  61 
molar  teeth,  including  the  time  spent  on  the  failures :  286  hours  30 
minutes. 

It  should  be  kept  in  mind  that  the  foregoing  time  records  do  not 
include  the  time  necessary  to  fill  the  canals,  and  further  that,  for  this 
work,  no  time  was  consumed  to  adjust  rubber  dams  and,  in  other  ways, 
observe  the  rules  of  aseptic  surgery. 

Three   things   in   particular   are   responsible   for  the 

OmCa^u'tlriSi?     "^^"^  failures:      (i)    Attempts  to  speed  the  work. 

(2)  Lack  of  access.     (3)  Devoting  time  and  thought 

to  excessive  enlargement  of  the  canals  near  the  pulp  chamber  instead 


CANAL   SURGERY  AND    ORAL   INFECTION 


459 


student's 
number 


1 
2 
3 
4 
5 
6 
7 
8 
9 

10 

11 

12 

13 

14 

15 

16 

17 

18 

19 

20 

21 

22 

23 

24 

25 

26 

27 

28 

29 

30 

31 

32 

33 

34 

35 

36 

37 
38 
39 
40 
41 
42 
43 
44 
45 
46 
47 
48 
49 
50 
51 
52 
53 
54 
55 
56 
57 
58 
59 
60 
61 
62 
63 

Totals 


The  tooth 
fiUed 


Time  devoted 
to  opening 
the  canals 

of  the 
teeth  filled 


U.  2nd  Mol. 
U.  1st  Mol. 
U.  2nd  Mol. 
U.  2nd  Mol. 
U.3rd  Mol. 
L.  2iid  Mol. 
U.  2nd  Mol, 
L.  1st  Mol 
U.  2nd  Mol 
L.  1st  Mol 
L.  1st  Mol 
U.  1st   Mol 

Student 
U.  1st  Mol. 
L.  1st  Mol. 
Student 
L.  2nd  Mol. 
L.  2nd  Mol. 
U.  2nd  Mol 
U.  2nd  Mol. 
U.  1st  Mol. 
U.  2nd  Mol. 
U.  2nd  Mol 
L.  1st  Mol. 
U.  2nd  Mol. 

L.  2nd  Mol. 

U.  1st    Mol. 

U.  1st   Mol. 

L.  2nd  Mol. 

U.  2nd  Mol. 

L.  1st    Mol. 

U.  1st    Mol. 

U.  1st   Mol. 

U.  1st    Mol. 

U.  2nd  Mol. 

L.  2nd  Mol. 

U.  1st   Mol. 

U.  2nd  Mol. 

L.  1st   Mol. 

L.  1st    Mol. 

U.  1st   Mol. 

U.  2nd  Mol. 

L.  2nd  Mol 

U.  1st   Mol. 

L.  2nd  Mol. 

L.  2nd  Mol. 

L.  2nd  Mol 

U.  2nd  Mol 

U.  1st   Mol. 

U.  1st   Mol. 

L.  2nd  Mol. 

L.  1st   Mol. 

U.  3rd  Mol 

U.  1st    Mol. 

U.  1st   Mol. 

U.  Ist   Mol. 

U.  1st   Mol. 

U.  1st   Mol. 

U.  1st   Mol. 

L.  1st   Mol. 

U.  1st   Mol. 

U.  1st   Mol. 

L.  2nd  Mol. 

61 


30 
20 
15 
:45 
:30 
15 
:00 
30 
:45 
40 
;30 
:30 

failed  to  hand 

1:00 

1:30 

faOed  to  hand 

1:35 

:45 

2:15 

2:30 

1:50 

1:30 

3:05 

2:30 

3:05 

:35 

:40 

3:15 

:35 

2:30 

:15 

2:00 

:55 

4:45 

1:30 

1:00 

3:00 

1:00 

:55 

:45 

1:15 

1:00 

:50 

4:30 

2:00 

2:00 

2:00 

:30 

:30 

1:30 

1:00 

1:15 

:30 

5:00 

2:40 

:25 

1:15 

2:00 

1:30 

1:30 

4:00 

2:00 

:40 

100:35 


The  number 

of  teeth 

discarded 

after  efforts 

to    open    the 

canals 


0 
6 
22 
1 
3 
4 
2 
2 
2 
0 
1 

in  work 
2 
3 

in  work 
5 
3 
1 
2 
1 
1 
5 
4 
5 
1 
4 
0 
0 
2 
3 
0 
1 
4 
3 
2 
2 
0 
1 
1 
5 
3 
0 
1 
11 
2 
0 
4 
5 
0 
1 
0 
8 
4 
0 
3 
3 
0 
1 
3 
9 
0 
0 


Time 

devoted 

to  teeth 

which  were 

discarded 

after  efforts 

to    open    the 

canals 


Total 
teeth 
used 


4:00 

0 

5:00 

13:00 

1:00 

2:30 

2:00 

1:30 

2:45 

3:15 

0 

2:00 

1:30 
3:00 

5:00 
3:00 
5:15 
2:30 
1:30 
3:00 
6:00 
7:30 
5:00 
:45 
1:10 

0 

0 
6:00 
6:00 

0 
1:15 
5:00 
4:00 
1:45 
1:30 

0 

1:00 

:50 

2:30 

2:45 

0 

1:30 

13:00 

1:15 

0 
4:00 
6:10 

0 
3:30 

0 

10:00 

6:00 

0 
3:15 
6:00 

0 
2:00 
5:30 
9:00 

0 

0 

185:55 


3 

1 

7 

23 

2 

4 

5 

3 

3 

3 

1 


3 

4 

6 
4 
2 
3 
2 
2 
6 
5 
6 
2 
5 
1 
1 
3 
4 
1 
2 
5 
4 
3 
3 
1 
2 
2 
6 
4 
1 
2 
12 
3 
1 
5 
6 
1 
2 
1 
9 
5 
1 
4 
4 
1 
2 
4 
10 
1 
1 


Total  time 

devoted  to 

efforts  to  open 

the  canals  in 

a  molar  before 

success  was 

attained 


4:30 
1:20 
7:15 
13:45 
1:30 
3:45 
3:00 
4:00 
3:30 
4:55 
:.30 
4:30 

2:30 
4:30 

6:35 
3:45 
7:30 
5:00 
3:20 
4:30 
9:05 
10:00 
8:05 
1:20 
1:50 
3:15 

:35 
8:30 
6:15 
2:00 
2:10 
9:45 
5:30 
2:45 
4:30 
1:00 
1:55 
1:35 
3:45 
3:45 

:50 

6:00 

15:00 

3:15 

2:00 

4:30 

6:40 

1:30 

4:30 

1:15 

10:30 

11:00 

2:40 

3:40 

7:15 

2:00 

3:30 

7:00 

13:00 

2:00 

:40 

286:30 


460 


APPENDIX 


of  using  very  small  broaches  to  trace  the  canals  to  the  ends  of  the  roots. 

A  friend  of  mine,  a  keen  observer,  declares  that  "  there  are  not  ten 

dentists  in  the  world  who  consistently  open  molar  teeth  sufficiently  to 

make  it  a  physical  possibility  to  open  the  canals  to  the  end."    It  is  unfor- 


Fig.    490.      Canal   fillings  m   sixty-one   molar   teeth.      The   work   was   done  by   Junior    dental   stu- 
dents of  the  Indiana  Dental  College,  academic  year  1915-1916.     Though  the  canals  of  all  of  the 
teeth   were   opened   through   the   end,    Fig.    490    represents   only   the   first   effort   to    fill   them   and 
many  of  them  are  very  imperfectly  filled. 

tunate  that  the  phrase  "  enlarge  canals  "  is  in  such  common  use ;  it  makes 
us  think  of  the  operation  in  the  wrong  way.  The  psychic  influence 
would  be  better  if  we  should  discard  the  phrase  "  enlarging  canals  "  for 


CANAL    SURGERY    AND    ORAL    INFECTION 


461 


opening  canals.  The  operator,  intent  on  opening  canals,  has  his  mind 
focused  on  the  place  he  wishes  to  reach — the  end  of  the  root — while  the 
man  enlarging  canals  has  his  mind  fixed  essentially  on  just  that  part  of 
the  canal  he  is  enlarging. 

From  a  study  of  Figure  490  and  chart  relating  to  it,  it  would  seem 
that,  if  given  the  economic  opportunity,  dentists  should  be  able  to  fill  the 
canals  of,  say,  about  one  out  of  three  molars,  at  least.  (In  the  past,  I 
should  say,  hardly  one  out  of  a  thousand  has  been  filled.)    For,  admitting 


Fig.  491.     Crooked  canal  of  upper  molar  filled  to  the  end.      (By  Dr.  Ottolengui,  N.  Y.  C.) 


the  students'  advantage  in  working  on  extracted  teeth  instead  of  teeth  in 
the  mouth,  it  is  not  unfair  to  presume  that  dentists  are  more  skillful  than 
junior  dental  students.  What  the  very  skillful  dentist  may  hope  to  do 
is  illustrated  in  Figure  491,  an  upper  molar  filled  by  Dr.  Ottolengui. 


Oral  Tnfcction* 

Reference  to  the  interpretation  of  radiographs  to  determine  oral  in- 
fection has  already  been  made  in  Appendix  to  Chapter  VI,  under  Mis- 
takes Numbers  28  and  29,  and  just  following  Mistake  Number  41. 

The  first  thing  to  be  said  about  evidence  of  infec- 
6»idcncc  of  Tnfectlon     tjon  which  can  be  seen  in  radiographs  is  to  emphasize 
the  fact  that  one  cannot  see  infection  in  radiographs; 
one  sees  only  evidence  of  infection.     Like  all  other  evidence,  it  may  be 
true  and  conclusive,  it  may  be  meager,  or  it  may  be  false — the  diagnos- 
tician must  judge  which. 

The  pulpless  teeth  seen  in  radiographs  may  be  classified  as  follows : 
( I )  Those  which  show  well-filled  canals  and  no  bone  change  in  the 
periapical  region;  (2)  those  which  show  imperfectly  filled  canals  and  no 
bone  change  in  the  periapical  region;  (3)  those  which  show  well-filled 
canals  and  bone,  or  root,  destruction  in  the  periapical  region,  and  (4) 
those  which  show  imperfectly  filled  canals  and  bone  or  root  destruction 
in  the  periapical  region.  (See  Chart  B  B  at  close  of  Appendix  to 
Chap.  VI.) 

(i)  Any  pulpless  tooth  may  be  a  source  of  infection — even  one 
with  a  well-filled  canal  and  no  radiographic  evidence  of  bone  involvement. 
I  believe  this  statement  is  true,  but  in  practice  I  assume  that  a  pulpless 
tooth  with  a  well-filled  canal  and  no  evidence  of  bone  change  about  it  is 
not  a  source  of  infection,  unless  the  history  of  the  case  and  the  symptoms 
are  such  as  to  definitely  contradict  this  assumption. 

(2)  Any  pulpless  tooth  with  a  faulty  canal  filling  but  showing  no 
evidence  of  bone  change  in  the  apical  region  is  likely  a  source  of  some 
infection.    It  is,  at  least,  a  potential  source  of  infection. 

(3)  Any  pulpless  tooth  with  a  well-filled  canal  showing  bone 
destruction  at  its  apex  may  be  considered  a  source  of  infection  unless  it 
has  but  recently  been  treated  and  there  has  not  been  time  for  bone  recon- 
struction to  occur.  A  canal  filling  which  reaches  the  end  of  the  canal 
but  does  not  fill  the  canal  full  is,  of  course,  not  a  good  canal  filling. 

(4)  Any  tooth  showing  an  imperfect  canal  filling  and  bone  destruc- 
tion at  its  apex  should  be  considered  a  focus  of  infection. 

From  the  foregoing  it  will  be  seen  that  whether  the  radiograph 
shows  us  something  which  indicates  infection  or  not  is  a  matter  of  deduc- 
tion. Thus,  local  symptoms,  if  there  are  any,  and  the  patient's  physical 
conditon  should  govern  our  interpretation  of  radiographs.  If  the  patient 
is  ill,  having  a  disease  which  might  be  caused  by  a  focus  of  infection,  and 

462 


CANAL   SURGERY  AND    ORAL   INFECTION  463 

the  conditions  revealed  by  the  radiograph  are  such  as  to  indicate  probable 
infection,  and  no  other  infection  can  be  found  in  other  parts  of  the  body, 
it  is  good  sense  to  assume  that  the  radiographic  evidence  of  probable 
infection  is  actually  evidence  of  infection  and  act  accordingly. 

Physicians  and  dentists  are  prone  to  disagree  regard- 
extraction  Of  tCCtl)  to     jng  the  advisability  of  extracting  teeth  to  overcome 
Ocmome  Infection  ,  •  r    .•        t-u  u  ^    u       -a  ■    a  i 

oral  mfection.     ihere  is  much  to  be  said  m  defense 

of  both.  Certainly  it  is  not  well  to  indulge  in  wholesale,  needless  sense- 
less extraction  of  teeth.  But  one  need  have  little  fear  of  this,  because 
of  objections  which  will  be  raised  by  the  patient. 

The  reasons  for  the  attitude  of  the  physician  are 
tl)C  Physician's         apparent — he    wants   the    patient   to    recover    health 

Position.  A  u     .u      i  ■  u      ^  J.      -hi 

and   he   therefore  wishes  to   remove  every  possible 

obstacle  to  such  a  recovery.    He  may  have  found  by  experience  that  very 

few  dentists  offer  any  evidence  to  prove  that  they  overcome  infection 

when  they  treat  a  tooth — and  therefore  the  only  way  he  can  feel  certain 

that  infection  will  be  overcome  is  to  have  the  teeth  extracted. 


„„   .    .1-       -  I  have  had  the  privilege  of  observing  the  manner  m 

dimination  ot  ,  .  ,    t^     ^     1        •  r  •,-.,.    ^1 

TnfCCtion  UlitbOUt        which  Dr.  Ottolengui  treats  cases  of  infected  teeth 

extraction.  ^nd  dental  abscesses  and  it  seems  to  me  a  physician 

has  a  perfect  right  to  expect  some  such  treatment,  and  evidence  that 
infection  has  been  overcome,  or  insist  upon  extraction. 

Dr.  Ottolengui's  practice  is  the  logical  one.  He  grows  bacteria 
from  the  abscesses  he  treats,  taking  the  cultures  from  the  canal  and  from 
beyond  the  end  of  the  root  through  the  canal.  He  treats  the  case  until 
he  can  no  longer  recover  a  culture ;  fills  the  canals  and  verifies  his  canal 
filling  with  radiographs.  Then — and  this  is  important — makes  subse- 
quent radiographs  to  see  what  periapical  bone  changes  occur. 

While  I  hope  I  do  not  underestimate  the  value  of  a  tooth,  I  do 
believe  that  in  some  instances,  at  least,  the  physiological  value  of  masti- 
cation is  overestimated.  For  example,  in  the  past,  the  restoration  to 
health  of  people  who  had  all  their  teeth  removed  and  false  teeth  made 
was  attributed  to  the  fact  that  the  false  teeth  enabled  them  to  masticate 
their  food.  H  you  will  recall  some  of  these  cases,  you  will  recollect 
that  the  restoration  to  health  began  to  occur  usually  before  the  false 
teeth  were  made  and  so  was  very  probably  due  to  the  elimination  of  oral 
infection. 


464  APPENDIX 

Continuance  Of         While  my  experience   leads  me  to  believe  that  it 
Infection  Hfter  seldom  occurs,  I  must  grant  the  possibility  of  a  con- 

cXtraction*  tinuance  of  infection  after  removal  of  an  abscessed 

tooth.  There  is,  therefore,  some  advantage,  and  I  can  see  no  disad- 
vantage, in  practicing  currettement  after  extraction  of  abscessed  teeth. 
When  an  abscess  cavity  persists  after  extraction  of  a  tooth,  it  is  some- 
times due  to  the  fact  that  the  approximating  tooth  is  abscessed — Figure 
189. 

The    subject    of    oral    infection    due    to    pyorrhea 
Pyoithea.  admits  of  little  discussion.     I   must  say,  however, 

that  many  cases  of  pyorrhea  are  treated  where, 
owing  to  the  amount  of  bone  lost,  a  cure  is  impossible.  (Figure  204.) 
It  is  remarkable,  however,  what  beneficial  general  effects  are  produced 
sometimes  by  treatment  of  incurable  pyorrhea  cases.  Perhaps  the  de- 
sirable, beneficial,  general  effects  on  cases  of  arthritis  and  other  systemic 
diseases  is  due  to  the  fact  that  the  surgical  treatment  for  the  pyorrhea  is 
equivalent  to  an  administration  of  a  bacterine  (usually  called  a  vaccine). 

Pursuant  to  this  idea  of  a  surgical  procedure  being 
^e  to  Se*f  xtracted  equivalent  to  an  injection  of  a  bacterine.  Dr.  Hartzell 
has  suggested  that,  in  cases  for  extraction  of  many 
infected  teeth — i.e.  abscessed  teeth  and  teeth  affected  with  pyorrhea — 
only  one  or  two  or  a  few  teeth  at  a  time  be  removed,  at  intervals.  There 
will  sometimes  be  an  exacerbation  of  symptoms — i.e.,  a  "  reaction  "■ — 
following  surgical  treatment,  quite  similar  to  the  "  reaction  "  following 
injection  of  a  bacterine. 

There  is  a  fundamental  difference  in  the  treatment 
PcrE^taTlnf^tiott       *~*^  dental  abscesses  today  as  compared  to  the  way 

in  which  they  have  been  treated  in  the  past.  Dental 
abscesses  should  no  longer  be  treated  as  a  local  disease.  To  state  it  dif- 
ferently, dentists  must  cease  to  treat  abscesses  and  commence  to  treat 
the  patient.  In  this  work  of  treating  the  patient  the  dentist  should  be 
willing  and  anxious  to  co-operate  with  the  patient's  physician.  Ever 
since  I  can  remember,  dentists  have  been  crying  for  physicians  to  recog- 
nize the  importance  of  the  mouth.  Physicians  do  recognize  the  hygienic 
importance  of  the  mouth  now  and — is  it  not  true? — dentists  are  crying 
because  they  do. 

Naming  the  methods  in  order  of  their  effectiveness  and  reliability, 
periapical  infection  may  be  treated  in  seven  ways:  (i)  By  extraction 
and  currettement.  (2)  By  extraction.  (3)  By  root  resection  and  cur- 
rettement.    (4)   By  currettement.     (5)   By  Ionization.     (6)   By  forcing 


CANAL    SURGERY   AND    ORAL    INFECTION  465 

some  drug,  such  as  phenolsulphonic  acid,  50  per  cent.,  or  tincture  of 
iodine,  3  or  4  per  cent,  in  water,  through  the  canal.  (7)  By  seahng 
volatile  drugs  in  the  pulp  canal. 

The  amount  of  bone  destruction  governs  to  a  great  degree  the  method 
to  be  employed — the  more  bone  destruction  there  is  the  more  effective 
the  method  of  disinfection  must  be.  (See  Charts  C  C  and  D  D  at  the 
close  of  Appendix  To  Chap.  VI.)  But  the  amount  of  bone  destruction 
is  only  one  of  the  things  which  governs  the  treatment  indicated.  The 
ability  of  the  operator,  the  health  of  the  patient,  the  condition  of  the  other 
teeth  in  the  mouth,  the  patient's  financial  and  social  standing,  the  time 
which  can  be  devoted  to  the  work  and  other  things  must  also  be 
considered. 

Perhaps  I  will  help  my  reader  most  by  showing  radiographs  of  cases 
which  have  been  treated,  and  then  let  him  judge  for  himself  what  par- 
ticular method  he  will  follow  in  any  given  case.  Before  doing  so,  let  me 
say  that,  unless  a  tooth  is  extracted,  the  use  of  post-operative  radiographs 
is  an  absolute  necessity. 

Later  developments  in  our  rapidly  growing  knowl- 

RCflCncration  Prow       ^^^^  regarding  oral  abscesses  may  prove  me  wrong 

eradication  Of  in  this,  but  just  now  (January,  19 17),  I  assume  that 

infection   has  been  overcome   if   I   get  a   complete 

bone  regeneration  in  the  abscess  cavity  in  about  a  year.     (While,  as  I  say, 

I  assume  that  infection  has  been  overcome  in  the  event  mentioned  above. 

I,  nevertheless,  recognize  the  lack  of  definite  knowledge  on  this  subject 

and  I  would  not  object  strenuously  to  the  removal  of  such  a  tooth  if  it 

gives  any  hope  whatever  of  benefiting  or  curing  a  very  sick  patient,  and 

it  was  the  patient's  and  the  patient's  physician's  desire  that  the  tooth  be 

removed.     I  might  consider  the  removal  of  the  tooth  the  "  drowning 

man's  grab  at  a  straw  "  but  I  would  not  refuse  the  one  about  to  drown 

that  last  privilege.) 

CASES 
Abscess    upper    lateral    and    central.      Particularly 

X^^f^  bad  case  on  account  of  bone  destruction  alonsf  sides 

il  anaB.  .  ...  ,,    .    ,.  ,         *'      . 

of  roots,   which  usually  mdicates  an  abscess  cavity 

very  deep  facio-lingually. 

Prognosis  at  time  treatment  was  started :  very  doubtful. 

Treatment :  Phenolsulphonic  acid,  50  per  cent.,  through  apex,  out 
fistula,  three  times,  at  intervals  of  about  five  days.  Dressing  in  canals 
during  intervals :  formo-cresol  at  times,  cresol  or  creosote  at  other  times. 
Canal  filling:  Callahan  method. 


466 


APPENDIX 


Result :  Secession  local  symptoms.  Fistula  closed.  No  general 
symptoms.  Radiograph,  Fig.  492A,  made  in  April.  Radiograph,  Fig. 
492B,  made  in  September,  five  months  later.     Fig.  492B  shows  con- 


Fig. 


492A.      Abscess    upper   lateral    and    cen- 
tral;  before  treatment. 


Fig.  492B.  Same  case  as  Fig.  492A,  five 
months  after  treatment.  _  Note  considerable 
bone  reconstruction.  Disinfected  with  phe- 
nol-sulphonic  acid. 


Fig.  493A. 


Abscess  upper  lateral  incisor;  be- 
fore treatment. 


Fig.  493B.  Same  case  as  Fig.  493A,  five 
months  after  treatment.  Disinfected  with 
a  4  per  cent,  solution  of  tincture  of  iodin 
in  water.  More  canal-filling  material 
through  end  than  desirable,  but  apparently 
causing  no  irritation. 

siderable  bone  reconstruction.     (Operator,  Dr.  Karl  Kayser  of  Indian- 
apolis.) 

Abscess  upper  lateral  incisor. 
w'anO  Prognosis  at  time  treatment  was  started ;  good. 

Treatment :  Four  per  cent,  tincture  of  iodine  in 
water  through  apex,  three  times,  at  intervals  of  five  days.  Dressing  in 
canals  during  intervals :  f  ormo-cresol,  cresol  or  creosote.  Canal-filling : 
Callahan  method. 


CANAL  SURGERY  AND   ORAL  INFECTION  467 

Result:  Radiograph,  Fig.  493A,  made  in  April.  Radiograph,  Fig. 
493B,  made  in  October,  six  months  later.  Fig.  493B  shows  bone  recon- 
struction in  spite  of  the  amount  of  gutta  percha  through  end.     Ex- 


rig.    494 A.      Abscess    lower    bicuspid;    before        Fig.    494B.      Same  case  as   Fig.   494A,  seven- 
treatment,  teen   months    after   treatment. 


Fig.     495A.       Abscess    upper    lateral    incisor;        Fig.    495B.       Same    case    as    Fig.    495A,    ten 
before   treatment.  months     after     treatment.       Disinfected     by 

ionization. 

cept  following  the  first  injection  of  iodine  there  were  never  any  local 
symptoms.  General  symptoms :  autointoxication,  which  disappeared  after 
treatment  of  tooth.  Patient  gained  twenty  pounds  in  three  months. 
(Operator,  Dr.  Carl  Emmert,  of  Indianapolis.) 

Abscess  lower  second  bicuspid. 
HflHd^R  Prognosis   at   time  treatment   was   started    (judging 

from  appearance  of  radiograph)  :  fair. 
Treatment :  Treated  from  April  first  to  April  eighteenth,  then  filled 
by  Callahan  method.     Sodium  and  potassium  compound  used  to  sterilize 
canals.     Dressings  sealed  in  canals  not  known. 

Result :  Local  symptoms  subsided,  fistula  closed.     Figure  494A  was 
made  April  i,  19 15.    Radiograph,  Fig.,494B,  was  made  in  August,  191 6, 


468 


APPENDIX 


Tig.  495 
B  ana  B. 


seventeen  months  later.  Figure  494B  shows  complete  bone  reconstruc- 
tion built  in  about  the  root  and  filling  material  through  the  end  of  the  root. 
(Operator,  Dr.  A.  W.  Bark,  of  New  York  City.  I  am  indebted  to  Dr. 
A.  Berger,  of  New  York  City,  for  bringing  this  case  to  my  attention.) 

Abscess  upper  lateral  incisor. 

Prognosis  at  time  treatment  was  started  (judging 
from  appearance  of  radiograph)  :  fair  or  good. 
Treatment :  Ionization,  3  per  cent,  zinc  chlorid  solution  on  cotton  in 
pulp  chamber,  zinc  electrode  fastened  to  positive  pole  against  saturated 
cotton,  negative  pole,  sponge  on  cheek,  one-half  milliampere  for  five 
minutes.  (Patient  did  not  feel  current.)  Three  treatments:  first  treat- 
ment, February  eighteenth ;  second  treatment,  March  eighth,  eighteen 
days  later ;  third  treatment,  March  sixteenth,  eight  days  later.  Canals 
filled  March  sixteenth. 


Fig.     496A. 


Abscess    upper    lateral    incisor; 
before    treatment 


Fig.    496B.       Same    case    as    Fig.    496A,    six 
months    after   treatment. 


Result :  Figure  495A  was  made  in  February.  Figure  495B  was  made 
in  December,  ten  months  later.  Figure  495 B  shows  the  abscess  cavity 
entirely  filled  with  new  bone.  There  is  considerable  canal  filling  through 
the  end — it  is  gutta  percha.  The  fistula  closed  after  treatment.  (Oper- 
ator, Dr.  Marcus  Straussberg,  Newark,  N.  J.  Items  of  Interest,  April, 
1916.) 

Abscess  upper  lateral  incisor,  canal  not  filled. 
Prognosis  at  time  it  was  decided  to  resect  root :  con- 
sidering the  nature  of  the  treatment  decided  upon, 
excellent. 

Treatment:  Root  resection  and  curettement,  end  of  canal  filled  with 
amalgam.     (Filling  the  end  of  an  unfilled  canal  with  amalgam  is  especially 


Tig.  496 
H  and  B. 


CANAL  SURGERY  AND    ORAL   INFECTION  469 

advantageous  when  the  tooth  has  a  post  crown  on  it.  To  the  writer,  this 
procedure  seems,  in  most  cases,  very  good  practice.  If  the  canal  is  filled 
just  previous  to  the  root  excision  it  is  hardly  necessary,  for  the  operator 
is  then  sure  the  canal  is  filled  full.  But  even  when  the  radiograph  shows 
us  a  canal  filling  reaching  to  the  end  of  the  root  or  to  the  point  where 
the  root  is  to  be  cut  off,  we  cannot  be  sure  the  canal  is  filled  solid  full — 
hence,  the  advisability  of  sealing  the  end  with  amalgam.  As  far  as  I 
know,  this  procedure  is  original  with  Dr.  C.  D.  Lucas,  of  Indianapolis.) 

Result :  Figure  496A  was  made  in  April.  Figure  496B  was  made  in 
October,  six  months  later.  Figure  496B  shows  regeneration  of  bone. 
Patient  recovered  from  keratitis  within  three  weeks  after  operation. 

There  is  a  belief  among  many  dentists  that  the  root  end  is  excised  be- 
cause it  is  rough  and  therefore  a  mechanical  irritant.  A  roughened  root 
end  is  a  necrotic,  infected  root  end  and,  for  this  reason,  it  is  excised. 

I  must  make  the  statement,  as  we  consider  the  matter  of  bone  recon- 
struction, that  I  have  seen  it  occur  following  disinfection  of  the  canals 
of  the  tooth  and  the  pus  sinus  when  the  canals  zvere  not  fiWed  to  the  end. 


Some  Essentials  Kegarding  the  Cccbnic  of  Tottization. 

Ionization  is  a  process  of  introducing  drugs  into  tissue  by  means  of  a 
unidirectional  electric  current.  I  take  pleasure  in  recommending  the  book, 
"  Dental  Electro-Therapeutics,"  by  Dr.  Ernest  Sturidge ;  publishers,  Lea 
&  Febiger,  as  an  authoritative  work  on  this  subject.  Prinz's  "  Dental 
Materia  Medica  and  Therapeutics  (Mosby,  St.  Louis),  also  carries  a  fine 
chapter  on  this  subject. 

The  process  of  ionization  seems  to  the  writer  to  hold  great  possi- 
bilities. The  principle  of  its  application  is  illustrated  in  Figure  497. 
When  some  drugs  are  used ;  iodine,  for  example,  the  polarity  must  be 
changed  from  that  indicated  in  Figure  497. 

'  Figure  498  is  an  ionization  machine.  We  see  the  following  parts : 
(i)  The  main  switch,  (2)  the  pole  changing  control,  (3)  the  rheostat. 
(4)  the  milliammeter,  (5)  the  pilot  light. 

The  following  are  elementary  points  regarding  ionization  calculated 
to  help  the  beginner : 

Turning  on  the  current:  When  connections  are  all  made,  advance 
rheostat  slowly.  Stop  when  there  is  sensation ;  wait,  then  advance  slowly 
again.     Do  not  cause  pain. 

Strength  of  current:  Use  anywhere  from  one-half  to  five  milli- 
amperes. 


470 


APPENDIX 


Time  of  ionization  treatment :    About  five  to  ten  minutes. 

Number  of  treatments  and  time  of  intervals:  About  three  treatments 
at  intervals  of  about  five  days. 

Turning  off  the  current:  Turn  the  rheostat  slowly  (not  as  slowly  as 
it  was  advanced,  however)  to  avoid  pain.  Turn  current  off  before  re- 
moving electrode. 

AN  IONIZATION  REFERENCE  CHART. 


Drug. 

Put  the 
Drug  on 

Wrist  or  Indif- 
ferent Electrode 

{Moisten  with 
water). 

Iodine. 
(Aqueous  solution  or  equal  parts  tincture  and 
water  or  Lugol's  Solution.) 

Negative  Pole. 

Positive. 

Zinc  Chloride. 
3%  solution  in  water  or 
a  pure  zinc  electrode  with  a  solution  of  Sodium 
Chloride  in  the  canal. 

Positive  Pole. 

Negative  Pole. 

*Copper  Sulphate. 
2%  solution  in  water. 

Positive. 

Negative. 

Cocaine  Hydrochloride. 
Any  desired  strength  solution  in  water. 

Positive. 

Negative. 

H2O2 
full  strength  as  supplied  by  pharmacist. 

Negative. 

Positive. 

*Emetine  Hydrochloride. 
4%  in  water. 

Positive. 

Negative. 

*Silver  Nitrate. 
3%  in  water. 
Argyrol  20%. 

Positive. 

Negative. 

^ 

I 

(        -       ■    . 

1    J 

0M> 

Fig.    497.       Illustrating    the 
principle    of    ionization. 


Fig.     498.        An     ionization 
machine — wall   type. 


CANAL    SURGERY   AND    ORAL    INFECTION  471 

Some  Points  Redaraind  Sterilization  and  tbc  Practice  of 
Jlseptic  Pulp  €anal  OPork. 

The  hands:  Scrub  with  soap  and  water,  then  handle  nothing  but 
sterilized  instruments  and  accessories.  After  scrubbing-,  if  it  is  desired  to 
have  the  hands  more  surgically  clean,  dip  in  bichloride  of  mercury  solu- 
tion, I  :iooo,  then  distilled  water,  then  70  percent,  ethyl  alcohol. 

Instruments:  Boiling  water  for  twenty  minutes.  Two  percent,  bi- 
carbonate of  soda,  also  two  per  cent,  phenol  may  be  added  to  water  if 
desired. 

Accessories  other  than  instruments  should  be  sterilized  in  a  steam 
sterilizer,  which  admits  of  turning  the  steam  into  or  out  of  the  sterilizing 
chamber.  The  technic  for  the  use  of  such  a  sterilizer  consists  first,  of 
course,  in  placing  the  articles  to  be  sterilized  in  the  sterilizing  chamber : 
Heat  for  about  twenty  minutes  before  the  steam  is  turned  into  the  steril- 
izing chamber.  Turn  steam  into  chamber  for  thirty  minutes.  Turn 
steam  out  of  sterilizing  chamber,  leaving  heat  on  for  about  twenty  min- 
utes. This  dries  the  sterilized  articles.  (The  Wilmot  Castle  Company, 
Rochester,  N.  Y.,  makes  steam  sterilizer  of  the  type  the  writer  has  in 
mind.) 

Napkins  and  linens  of  all  sorts,  paper  canal  points,  cotton,  cotton 
sponges  of  all  si::es:  Wrap  in  gauze  or  unbleached  muslin,  pin  shut, 
sterilize  in  steam.     Do  not  open  packages  until  ready  to  use. 

Rubber  Dam:  Cut,  lay  between  layers  of  muslin,  sterilize  in  steam. 
Paint  after  its  adjustment  with  70  per  cent,  alcohol,  painting  the  teeth  in- 
cluded in  the  dam  adjustment.  Tincture  of  iodin  may  be  used  also  if 
desired. 

Cotton  Swabs  on  Broaches:  By  using  a  broach  holder  for  the  dental 
engine,  a  great  number  of  smooth  broaches  may  be  nicely  wrapped  with 
the  desired  amount  of  cotton,  then  sterilized  with  steam.  Wrap  in  muslin, 
sterilize,  then  open  wrapping  only  when  ready  to  use. 

Gutta-Percha  Points:  May  be  sterilized  in  steam.  Do  not  allow  the 
points  to  touch  one  another  when  subjected  to  the  heat  or  they  will  stick 
together.     Keep  in  70  per  cent,  alcohol. 

After  sterilization,  it  is  expedient  to  keep  all  pulp  canal  paraphernalia 
in  a  formaldehyde  "  sterilizer  "  (  ?)  or  case  where  nothing  else  is  kept. 


472 


APPENDIX 


In  further  consideration  of  the  matter  of  asepsis  and 
Dr,  Best's  CbiirtS.       infection,  a  perusal  of  Dr.  Best's  Charts  VI  and  VII 
will  prove  to  be  instructive. 


Provable    Causes    or    Pemapicai.    Abscesses 


-'  CoTOf    CR  FhflOusarXNTS 
r""_    IN  ^jLD   lA-iAlS 

I.   rp'jfi  CaPosed 


J  r-    BROrtChCS    W'lTi 
L    -  '  -X    BEF  CE    ^\AriKO 


PJL"  l5^ 


Chart  VI.  "  In  case  we  have  been  guilty  of  any  of  these  conditions,  we  have  contributed  our 
share  to  the  great  number  of  infected  pulpless  teeth.  Arsenic  is  dangerous  and  unnecessary. 
Periapical  tissues  are  frequently  destroyed  by  powerful  drugs  sealed  in  canals,  and  these  areas 
may  become  the  seat  of  infection  of  secondary  origin,  hemotogenous  origin."     Dr.  Elmer  S.   Best. 

Chart  yil.      "  Contains  some  practical  hints  which  will  assist  us  in  having  more  satisfactory  re- 
sults with  our  operation.      In  dental  surgery,  where  we  come  in  contact  with  the  patient's  system, 
.  the  same  principles  apply  as  in  surgery."     Dr.   Elmer  S.  Best. 


Some  essentials  Regaraiiid  CecDnic  of  Tnoculatittd  Culture 
media  from  tbe  Canals  of  Ceetb 


Recommend  little  book,  "  Laboratory  Methods,"  by  Williams  & 
Williams  (Mosby,  St.  Louis). 

Culture  media  can  be  purchased  from  Parke,  Davis  &  Company,  and 
other  reliable  manufacturers  of  biologic  preparations.  Suggested  media : 
Ascites  dextrose  agar  and  dextrose  bullion. 

Technic:  (i)  Flame  platinum  inoculating  needle.  (2)  Insert 
platinum  needle  in  canal  of  tooth.  (3)  Remove  needle  from  tooth.  (4) 
Flame  cotton  in  mouth  of  culture  tube.  (5)  Remove  cotton.  (6)  Flame 
mouth  of  culture  tube.  (7)  Make  plant  in  culture  with  needle.  Avoid 
touching  sides  of  culture  tube  with  needle.     (8)   Flame  mouth  of  culture 


CANAL   SURGERY   AND    ORAL   INFECTION  473 

tube.  (9)  Flame  cotton.  (10)  Reinsert  cotton  in  tube.  (11)  Flame 
cotton.     (12)  Within  an  hour,  place  tube  in  incubator. 

An  electric  incubator  9  x  9  x  12  inches  (inside  dimensions),  suitable 
for  dental  use,  can  be  obtained  from  The  Chicago  Surgical  and  Elec- 
trical Company,  Chicago,  Illinois. 

The  incubator  temperature  should  be  about  37^°  C.  A  growth  will 
usually  occur,  if  at  all,  in  from  forty-eight  to  seventy-two  hours. 

The  matter  of  examining  cultures  and  determining  the  nature  of  the 
organism,  obviously,  cannot  be  considered  here.  If  possible,  this  work 
should  be  turned  over  to  an  expert  laboratory  man. 


Fig.   499A.      Three  apical  foramina  in  lower  bicuspid  filled  by  the  Callahan  method. 


Cbe  Cccbnic  of  Openiitd  ana  TilHttd  Pulp  £mnH 

Certainly  it  is  not  out  of  place  to  include  in  this  chapter  something 
regarding  pulp  canal  technic. 

No  man  in  the  world  is  better  fitted  to  describe  this  technic  than 
Dr.  John  Callahan,  of  Cincinnati,  who  has  generously  granted  me  per- 
mission to  print  the  following  two  papers  by  him :  one,  "  Root  Canal 
Preparation  "  ;  the  other,  "  Root  Canal  Filling." 

Figure  499A  is  a  radiograph  of  a  lower  bicuspid.  It  shows  the  main 
canal  branching,  at  the  apex,  into  three.  All  three  of  these  small  canals 
and  apical  foramina  are  filled.  As  far  as  I  know,  this  can  be  done  only 
by  the  Callahan  method. 


474 


APPENDIX 


Root  €andl  Preparation. 

By  J.  R.  Callahan,  D.D.S.,  Cincinnati,  Ohio 
It  is  certain  that  much  may  be  judiciously  argued  in  favor  of  the 
drill,  or  of  chemical  and  mechanical  treatment  for  root  preparation,  and 
there  is  something  to  be  said  against  each  agent  or  combination  of  agents, 
and  that  is  what,  on  the  present  occasion,  I  have  to  say. 

To  state  one  argument  is  not  necessarily  to  be  deaf  to  all  others,  and 
that  a  man  has  written  a  book  of  travels  in  Russia  is  no  reason  why 
he  should  never  have  been  in  Africa. 

Whether  it  be  a  tooth  from  which  a  devitalized  pulp  is  to  be  re- 
moved after  arsenical  application  or  pressure  anaesthesia,  or  the  opening 
and  cleansing  of  a  pulp  canal  that  shows  a  moist  or  dry  gangrenous 
tissue,  or  any  or  more  of  the  numerous  pathological  pulp  condition  or 
conditions  beyond  the  root  end,  the  goal,  the  strategic  point,  is  the  apical 
foramen  or  foramina :  foramina  in  ninety  per  cent,  of  adult  teeth. 

It  is  then  the  duty  of  the  operator  to  obtain  a  sterile  and  as  direct 
and  as  free  a  passage  to  the  strategic  point  as  the  nature  of  the  root 
canal  will  permit.  It  does  not  meet  the  present  day  requirements  to  say, 
as  do  some  of  our  text  books  and  essayists,  "  open  the  root  canals  to  the 
end."  Our  inquiry  is,  how  is  this  seemingly  simple  little  thing  to  be 
done  ? 

To  undertake  the  opening  and  preparation  of  a  root  canal  should 
indicate  that  the  dentist  recognizes  the  necessity  for  removing  every 
atom  of  devitalized  tissue,  having  the  canal  throughout  its  entire  length 
and  in  all  of  its  ramifications,  including  the  dentinal  tubuli  sterile  and 
in  such  shape  and  condition  that  the  canals,  the  tubuli,  the  foramina  may 
be  permanently  sealed  or  filled. 

Diagnosis,  filling  of  canals  or  treatment  of  conditions  around  and 
about  the  root,  are  not  to  be  discussed  further  than  may  be  necessary  to 
make  clear  the  reasons  for  certain  steps  to  be  mentioned. 

The  dentist  should  on  every  possible  occasion  avail  himself  of  the 
advantage  to  be  obtained  through  having  one  or  several  radiographs  be- 
fore him  for  comparison  or  study.  We  cannot  be  reasonably  sure  of  the 
effectiveness  of  our  efiforts  without  such  assistance,  nor  can  we  be  ab- 
solutely certain  with  them.  Many  of  the  pictures  thrown  on  the  screens 
and  printed  in  our  journals  as  evidence  of  perfect  technic  and  results  are 
about  as  clear  as  rabbit  tracks  in  the  snow  on  a  windy  day,  when  it  is 
a  difiicult  matter  to  determine  whether  brother  rabbit  is  going  or  coming, 
the  strategic  point  being  conspicuously  absent.  Improved  apparatus  and 
technic  will  some  day  overcome  these  shortcomings.  Inasmuch  as  the 
largest  number  of  dentists  are  for  one  reason  or  another  deprived  of  the 


CANAL   SURGERY   AND    ORAL   INFECTION  475 

valuable  assistance  of  the  X-ray,  and  our  literature  is  being  surcharged 
with  most  accurate  information  in  this  line,  let  us  then  on  the  present 
occasion  keep  in  mind  the  great  majority  who  get  along  the  best  way 
possible  without  this  expensive  adjunct. 

All  operations  upon  the  root  canal  from  begin- 

HseVtiC  0»cratiOtt       ^^"^  ^°  completion  are  purely  surgical  and  should  be 

KCCOmtnendC^.  conducted  upon  surgical  principals;  this  being  true, 

the    maintenance    of    aseptic    conditions    is    of    first 

importance. 

Radiated  heat  and  superheated  steam  in  combination  is  the  only  ac- 
ceptable method  for  the  steriHzation  of  instruments,  cotton,  paper  points, 
gutta-percha  points,  etc. 

Steam  chests  that  are  best  adapted  to  this  use  are  known  as  the 
Pentz  System,  made  by  the  Santiseptic  Manufacturing  Co.,  Tompkins- 
ville,  N.  Y.,  and  a  double  chambered  steam  chest  made  by  the  Wilmot 
Castle  Co.,  of  Rochester,  N.  Y. 

The  opening  of  the  pulp  chamber  should  be  ac- 
OveninaintO  complished  with  as  little  disturbance  of  the  devital- 

Pulp  Cbaittber.  ized  pulp  tissue  as  may  be  possible :  to  this  end  it 

will  be  well  to  cut  through  the  dentin  with  a  drill, 
then  use  carborundum  disks  and  stones,  keeping  the  carborundum  stones 
moistened  with  water  that  contains  a  liberal  supply  of  carborundum 
powder.  This  enables  the  stone  to  cut  rapidly  without  heating  the  tooth. 
Better  results  will  be  obtained  if,  while  using  the  stones  and  car- 
borundum powder,  all  of  the  tooth  crown  be  removed  that  interferes 
with  pulp  chamber  enlargements  that  may  be  necessary  in  getting  direct 
access  to  the  end  of  the  root. 

Sufficient  enamel  and  dentin  having  been  removed  to  give  a  clear 
view  of  the  pulp  chamber,  it  will  be  well  to  prepare  for  the  placing  of 
the  rubber  dam,  by  means  of  threads,  fine  polishing  strips,  separators  or 
by  whatever  means  necessary  to  insure  the  dam  going  to  place  with  little 
or  no  forcing.  There  should  be  no  leakage  whatever  about  any  of  the 
teeth  included  in  the  field  of  operation. 

If  the  cavity  margin  reaches  to  or  below  the 

_,  gum  line  then  a  copper  band  should  be  fitted  and 

Tacllitak  Use  cemented  to  place  about  that  tooth,  so  that  the  dam 

Of  Ktlbbcr  Dam.         ^nd  clamp  can  be  placed  upon  or  over  the  band  and 

tooth  without  danger  of  displacing  the  band.* 


*It  will  sometimes  be  practical  to  put  the  rubber  dam  clamp  on  the  tooth 
posterior  to  the  one  with  the  band  on  it  and  bring  the  dam  forward  to  mclude  the 
banded  tooth.— H.  R.  R. 


476  APPENDIX 

The    dam   being   in    place,   bathe   the   exposed 
RcmoVfll  Of  teeth,  rubber  dam  and  clamp,  etc.,  with  a  seventy 

Pulp  per    cent,    alcohol    solution    or    tinct.    iodine.      This 

strength  of  alcohol  is  a  more  .effective  germicide 
than  the  ninety-five  per  cent,  generally  used.  With  warm  air  dry  the 
cavity :  with  small  fissure  drill  make  a  circular  cut,  leaving  a  cap  of  den- 
tin over  the  pulp  chamber  which  may  be  removed  by  a  blast  of  air  or  a 
fine  excavator.  Having  exposed  the  pulp  it  will  in  many  cases  be  well 
to  toughen  or  harden  the  pulp  tissue  by  placing  a  drop  of  alcohol  and 
formalin  (about  five  per  .cent,  formalin)  on  the  devitalized  pulp  for  a 
few  minutes.  Then  with  hot  air  dry  the  pulp,  when  a  fine  broach  is 
passed  alongside  the  pulp  or  largest  branch  of  the  pulp.  Slightly  turn- 
ing or  rotating  the  broach  and  withdrawing  the  broach,  will  in  many 
cases  bring  the  entire  pulp,  including  the  smaller  branches  of  molar  pulps. 
Every  possible  effort  should  be  made  to  get  the  entire  pulp  at  the 
first  trial.  The  extracted  pulp  should  be  spread  on  white  paper  and 
examined  with  a  magnifying  glass  that  the  operator  may  know  the  loca- 
tion of  pulp  fragments  if  there  be  any. 

The    three    methods    of    procedure,    from    this 
■ '       Gkansiltd  point,  that  we  wish  to  discuss  briefly  are :  the  drill, 

(Canals*  the  sodium-potassium,  and  the  sulfuric  acid  and  soda 

bicarbonate. 
The  open  chamber  and  canals  should. first  be  washed  out  with  nor- 
mal saline  solution ;  dry,  then  place  shred  of.  cotton  saturated  with 
clove-oil  well  within  the  large  or  open  canal  to  remain  while  we  go  in 
search  of  the  very  minute  canals  that  may  be  so  small  that  it  is  a  difficult 
matter  to  find  them. 

Paint  the  floor  of  the  pulp  chamber  with  tincture 

jljj  ^1  of  iodine.     When  the  surplus  iodine  is  absorbed  by 

Canal  Drills.  a  cotton  pellet,  little  dark  spots  will,  in  most  cases, 

reveal  the  location  of  the  canals.     The  finest  Kerr 

drill,  manipulated  by  hand,  without  pressure,  will  enter  a  very  fine  canal 

by  gently  rotating  the   drill,   and  being  very   delicate   and  flexible  and 

threaded  like  a  screw,  will  in  most  cases  bring  away  the  remaining  pulp 

tissue,  when  the  canal  may  be  enlarged  by  gradually  increasing  the  size 

of  drills,  or  the  drills  may  be  worked  in  and  out  of  the  canals  as  files. 

.  .  These  flexible  drills  will  go  around  a  slight  curve  if  the  canal  is 
large  enough  to  give  the  instrument  free  play.  If  the  instrument  binds, 
at  or  near  the  curvature,  a  false  pocket  will  be  made  on  the  outer  wall 
of  the  canal  at  the  curve.  The  little  pocket  or  pit  in  the  dentin,  at  the 
point  indicated,  prevents  further  instrumentation  within  that  canal. 


CANAL   SURGERY  AND    ORAL   INFECTION  477 

Each  and  every  root  canal  is  more  or  less  of  a  law  unto  itself.  A 
correct  radiograph  is  of  inestimable  value.  In  the  absence  of  the  X-ray 
picture,  the  operator  will  be  greatly  assisted  by  making  a  pencil  sketch 
of  the  probable  shape  of  the  tooth.  In  this  way  his  memory  will  be 
refreshed  and  he  will  be  made  more  keen  and  alert  as  to  the  probable 
difficulties  ahead. 

In  some  cases  it  may  be  of  advantage  to  sink  a  shaft  in  the  root 
using  a  bud  drill,  following  the  fine  canal  from  a  third  to  a  half  the 
length  of  the  root,  following  the  canal  from  this  point  with  the  fine 
flexible  drill. 

By  being  patient  and  careful  many  of  the  finer  canals  may  be  opened 
to  the  foramen. 

It  is  possible,  however,  that  septic  matter  or  pulp  fragments  that 
may  become  septic,  have  been  forced  through  the  foramen  into  the 
apical  space. 

It  is  not  possible  that  the  multiple  foramina,  or  the  collateral  canals, 
or  the  connecting  canals  or  the  flat  thin  cancellous  spaces  between  the 
main  canals  in  double  roots  have  in  any  sense  been  opened  or  cleansed 

The  drills  in  many  such  roots  have  simply  drilled  holes  through 
organic  substance  in  various  stages  of  disintegration.  Such  substances 
cannot  be  washed  or  swabbed  out  but  are  left  within  the  canal,  some- 
times saturated  with  such  antispetic  medicaments  as  may  be  applied,  and 
finalty  incorporated  with  the  root  canal  filling. 

Schrier's  kalium-natrium,  or  sodium-potassium, 

^.^-..^  n<.^««..:..^        as  we   more   frequently  name   it,   is  a  concentrated 
$oaium-rot(i$$iutii        ,,   ,.  ,    .        ,  . , 

m^tbOd  of  alkali  caustic ;  explosive  when  in  contact  with  water, 

CrlCanSing  CaitalS*        yet  a  most  useful  agent  when  carefully  and  skillfully 

handled,     for    the    purpose    of     removing    organic 

substance  from  root  canals.     It  is  also  a  useful  adjunct  for  opening  and 

enlarging  root  canals  after  the  manner  advocated  by  Drs.   Rhein  and 

Ottolengui. 

If  the  dentist  will  moisten  a  spot  of  skin  on  the  back  of  his  own  hand 
and  place  thereon  a  small  particle  of  sodium-potassium  he  will  realize  at 
once  the  necessity  of  giving  close  attention  to  the  protection  of  the  patient, 
including  the  nostrils,  which  should  be  protected  in  some  way. 

All  the  pulp  tissue  that  is  within  reach  of  the  broaches  having  been 
removed,  small  particles  of  the  sodium-potassium,  size  of  a  pin  head 
if  placed  where  the  very  fine  canals  should  be,  the  dentin  being  moist  will, 
by  dissolving  the  organic  substance,  reveal  the  elusive  anterior  canals  of 
lower  molars  or  buccal  canals  of  upper  molars.    These  canals  after  being 


478  APPENDIX 

located  and  having  been  exposed  to  the  action  of  the  sodium-potassium 
for  a  fevv?  minutes,  should  be  attacked  with  what  has  been  named  "  picks," 
Dr.  Rhein  having  devised  a  very  sufticient  instrument  under  this  name. 
An  instrument  will  be  illustrated  later  that  has  the  advantage  of  being 
more  rigid  and  also  having  interchangeable  points. 

These  picks,  with  assistance  of  the  sodium-potassium,  which  breaks 
down  the  organic  matrix  of  the  dentin,  converting  it  into  a  soapy-like 
mass,  which  acts  as  a  lubricant,  will  work  their  way  into  the  canal,  enlarg- 
ing and  sterilizing  in  a  most  satisfactory  manner. 

After  advancing  a  distance  into  the  canal,  if  the  pick  begins  to  bind 
or  lock,  thereby  becoming  a  piston  within  the  canal,  a  large  Gates- 
Glidden  drill,  from  which  the  point  has  been  ground,  may  be  used  to 
enlarge  the  lumen  of  the  canal  so  that  the  pick  may  work  more  freely. 

When  having  reached  the  region  of  a  curve  in  the  canal  or  a  near 
approach  to  the  foramen,  it  will  be  safer  to  use  a  finer  instrument,  a 
Donaldson  broach,  from  which  the  barbs  have  been  partially  removed,  for 
the  purpose  of  negotiating  the  curve  if  possible ;  also  to  eliminate  as  much 
as  possible  the  piston  effect  of  the  larger  instrument  that  might  force  the 
caustic  contents  of  the  canal  into  .the  region  beyond  the  foramen,  and  do 
damage  that  will  be  difficult  to  control. 

I  have  had  two  severe  burns  in  my  practice  from  this  cause.  In  one 
case  the  tooth  had  to  be  extracted,  and  the  second  one  I  fear  will  be 
lost. 

Chemical  substances  which  cause  death  and  degenera- 
*  tion  of  tissues  are  called  caustics. 

Alkalies,  such  as  sodium-potassium  and  calcium. 

Acids,  such  as  hydrochloric,  sulfuric,  nitric,  arsenius  and  carbolic, 
and  the  salts  of  some  metals,  such  as  silver  nitrate,  zinc  chloride,  copper 
sulphate,  are  the  most  common  types  of  caustics. 

The  alkalies  and  metallic  salts  act  by  uniting  with  the  albumins,  act- 
ing as  albumin  solvents. 

"  The  caustic  alkalies  are  not  self-limiting :  they  penetrate  deeply 
into  the  tissues  and  destroy  the  albumin  of  the  mucous  surfaces,  the  horny 
tissues  and  the  external  skin." 

Necrosis,  followed  by  eschar  formation,  is  caused  by  strong  caustics, 
the  necrosis  involving  tissues  at  various  depths,  depending  upon  the 
strength  of  the  caustic,  the  nature  or  mode  of  its  action,  and  the  time  it  is 
allowed  to  act. 

"  Those  agents  are  best  suited  by  cauterization  which,  like  concen- 
trated  sulfuric  and   fuming  nitric  acid  and  silver  nitrate,  penetrate  to 


CANAL   SURGERY  AND    ORAL  INFECTION  479 

the  deeper  layers  of  the  skin  and  mucous  membrane  only  after  acting 
for  some  time." 

The  treatment  of  chemical  injuries,  of  recent  cases,  should  be  directed 
toward  neutralization  of  the  agent  before  it  penetrates  deeply. 

Chemists  and  apothecaries  usually  have  two  solutions  ready.  Acetic 
acid  or  vinegar  is  used  to  neutralize  the  alkalies,  while  a  solution  of 
sodium  bicarbonate  is  used  to  neutralize  the  acids. 

If,  for  any  reason,  it  is  suspected  that  sodium-potassium  has  passed 
beyond  the  foramen,  a  sulfuric  acid  solution  should  be  applied  quickly 
followed  by  soda  bicarbonate  solution. 

I  have  no  doubt  that  through  some  of  the  large  foramina,  at  least, 
the  caustic  has  wrought  harm. 

In  the  constricted  canals  and  in  the  constricted  apical   region  the 

use  of  sodium-potassium  is  frequently  indicated.    The  dangerous  qualities 

of  a  valuable  agent  should  not  cause  us  to  overlook  its  useful  qualities. 

Twenty   years    ago    sulfuric    acid    solution    and 

^.M^.uiM-a^ia  soda  bicarbonate  solution  came  into  use.* 

SUITUriC  HCItt  ^,  ,-..,,  ,    .        , 

method  of  J- he   sultunc  acid   is  used   for   the  purpose   of 

0lC(in$ind  ^aittllS*  softening  the  surface  of  the  pulp  canal  walls  to  per- 
mit the  passage  of  the  barbed  or  roughened  broaches 
to  and  fro  through  the  canal,  enlarging  the  canal  by  breaking  loose  the 
softened  dentin.  Soda  bicarbonate  solution  is  thereupon  injected  into 
the  canal  that  the  broken  down  dentin  and  other  disorganized  substances 
may  be  removed  from  the  canal  by  effervescence  caused  by  the  escape 
of  carbonic  acid  gas  that  is  the  product  of  the  neutralizing  action  of  the 
soda  bicarb,  upon  the  sulfuric  acid. 

This  reaction  leaves  the  canal  in  a  state  of  surgical  cleanliness.  This 
cannot,  to  my  knowledge,  be  said  of  any  other  method  or  agent. 

Twenty  years  is  a  long  time  for  a  method  or  theory  to  stand  prac- 
tically unaltered.  Notwithstanding  the  age  of  the  so-called  sulfuric  acid 
treatment  (which  might  much  better  have  been  entitled,  "  Sulfuric  acid 
and  soda  bicarb,  treatment"),  a  brief  resume  of  the  theory  and  practice 
of  the  doctrine  may  not  be  amiss. 

Concentrated  sulfuric  acid  is  also  an  active  escharotic.  The  acid 
caustics  act  by  burning  the  structure  with  which  they  come  in  contact. 

They  not  only  disintegrate  albumen  but  attack  many  other  organic 
substances.  The  breaking  up  of  inorganic  and  the  carbonization  of 
organic  substances  is  to  be  borne  in  mind. 

Limited  and  mild  caustics  when  applied  cause  an  inflammatory 
action,  depending  upon  the  strength  and  time  of  application. 


*  Given  to  the  profession  by  Dr.  Callahan. — Ed. 


48o  APPENDIX 

A  fifty  per  cent,  (by  volume)  solution  of  sulfuric  acid  will  soften 
cotton  on  the  carrying  instrument.  A  weak  acid  solution  gives  a  cor- 
respondingly weak  reaction  in  the  presence  of  the  soda  solution. 

The  strength  of  the  acid  solution  should  be  not  less  than  twenty 
per  cent,  and  not  above  forty  per  cent,  for  root  canal  work.  In  my  own 
practice  thirty  per  cent,  to  forty  per  cent,  aqueous  solution  or  commer- 
cial sulfuric  acid  by  volume  is  the  standard. 

Soda  bicarbonate  should  be  a  saturated  solution. 

In  relation  to  the  action  of  the  acid  solution  on  bone  tissue,  Mr. 
George  Pollack,  F.  R.  C.  S.,  Surgeon  to  St.  George's  Hospital,  says: 
"  Dilute  sulfuric  acid  does  not  affect  the  living,  acting  chemically  on  dis- 
eased bone  alone."  He  gives  the  following  experiments :  "  Portions  of 
dead,  diseased  and  healthy  bone  were  selected  and  subjected  to  the  action 
of  sulfuric  acid," 

viz. :  No.  I.     Dead  bone lo  grains 

2.  Diseased  bone   lO  grains 

3.  Healthy  bone  (middle  age) .  .    10  grains 

4.  Healthy  bone  (old  age) 10  grains 

"  Exposed  to  the  action  of  a  mixture  of  sulfuric  acid  and  water  one 
part  in  four,  for  three  days,  at  a  temperature  of  one  hundred  deg.,  the 
following  were  the  results : 

No.  I.     Dead  bone,  phosphate  of  lime  2  grs.     Carbonate  of 

lime  3.3  grs.  dissolved  in  the  mixture. 

No.  2.     Diseased  bone,  phosphate  of  lime  2  grs.    Carbonate  of 

lime  1.3  grs.  dissolved  in  the  mixture. 

Nos.  3  and  4.     In  both  specimens  of  healthy  bone  no  action 

took  place." 

Dr.  Garretson,  in  the  treatment  of  caries  of  the  maxilla,  recommends 
the  use  of  the  officinal  ordinary  sulfuric  acid. 

On  the  diseased  or  partially  disorganized  soft  tissues  the  solution 
will  have  a  corrosive  and  astringent  effect,  or  in  other  words,  will  break 
down  or  destroy  the  diseased  tissue,  leaving  a  fresh,  clear  field  for  nature, 
with  the  assistance  of  mild  antispetic  treatment,  to  take  care  of  herself. 

Why  does  not  sulfuric  acid  attack  and  destroy  divitalized  dentin? 
The  acid  at  first  attacks  the  tooth  substance,  breaking  down  the  lime- 
salts,  at  the  same  time  corroding  or  carbonizing  the  organic  substance, 
forming  a  new  compound,  thereby  establishing  a  barrier  to  the  further 
progress  of  the  acid. 

Prof.  Cassidy,  see  Dental  Chemistry  and  Materia  Medica,  says :  "  The 
acid  attacks  the  earthy  portion  forming  insoluble  calcium  sulphate  (Ca 
S04),  at  the  same  time  dehydrating  the  animal  or  gelatinous  portion, 
which  is  mainly  made  up  of  carbon,  hydrogen  and  oxygen.     These  two 


CANAL   SURGERY  AND    ORAL   INFECTION  481 

latter  elements  are  withdrawn  as  already  alluded  to,  leaving  the  inde- 
structible carbon  as  a  residue  to  be  incorporated  with  the  insoluble  sul- 
phate, producing  thus,  a  protecting  covering  to  the  unaffected  parts 
beneath,  against  further  inroads  of  the  causing  agents." 

This  protecting  covering  of  carbon  and  calcium  carbonate  are  re- 
moved or  scraped  away  by  each  excursion  of  the  rough  broach,  permitting 
the  acid  to  take  another  bite  at  the  dentin. 

The  same  chemical  and  mechanical  action  is  repeated  so  long  as  the 
broach  is  kept  in  motion  in  the  presence  of  the  acid  solution. 

The  depth  to  which  the  acid  affects  the  dentin  is,  unfortunately, 
immeasurably  small. 

It  would  be  a  great  advantage  to  the  work  in  hand  if  the  acid  would 
or  could  be  made  to  penetrate  further  into  the  dentin.  The  reason  why 
a  larger  area  of  the  dentin  is  not  at  once  affected  has  already  been  men- 
tioned. It  may  be  well  to  recall,  however,  that  dentin  consists  of  an 
organic  matrix,  a  reticular  tissue  of  fine  fibrils  richly  impregnated  with 
salts  of  calcium.  Traversing  the  matrix  are  long,  fine  canals  or  tubes, 
the  dentinal  tubules,  twenty-five  to  thirty  thousand  to  the  square  milli- 
meter. Immediately  surrounding  the  tubules  the  matrix  is  especially 
dense,  forming  a  lining  or  sheath  to  the  tubes,  known  as  the  dentinal 
sheaths  or  Neuman's  sheaths.  Neuman's  sheaths  are  insoluble  in  boiling 
sulfuric  acid. 

Sulfuric  acid  causes  delicate  steel  instruments 

IHi^thAd  flf  ^°  become  brittle  and  to  break  on  small  provocation, 

Jlpplying  HCid  leaving  small  pieces  of  steel  buried  within  the  canal. 

in  0(in(ll$*  This  unpleasant  accident  is,  as  a  rule,  due  to  the 

manner  of  manipulating  the  broach. 

For  very  fine  canals  the  barbs  should  be  partially  or  wholly  removed 
from  the  broach  or  a  fine  broach  can  be  made  from  gauge  twenty  to 
twenty-five  piano  wire.  These  broaches  should  be  cut  to  proper  lengths 
and  placed  in  a  rigid  holder  or  handle  that  will  hold  the  broach  in  a 
direct  line  with  the  line  of  force.  Either  pressure  or  traction  may  be 
applied  to  the  delicate  steel  point.  For  the  heavier  work,  digging  or 
enlarging  should  be  done  with  larger  and  stronger  points,  made  of  rough- 
ened steel  A  better  and  safer  instrument  may  be  made  by  taking  the 
largest  tantalum  silicate  plugger  points,  No.  104  or  105  S.  S.  W,  ,bend  to 
straight  line,  remove  from  the  handle,  file  or  grind  to  proper  shape,  and 
place  in  the  strong  right-angle  broach  holder  made  of  ivory.  This  makes 
a  most  effective  root  and  canal  excavator. 

The  metal  is  not  acted  upon  or  altered  in  any  way  by  acids.  This 
manner  of  enlarging  or  excavating  the  canal  to  a  large  extent  at  least 


482  APPENDIX 

eliminates  the  probability  of  making  a  false  tract  or  pocket  within  the 
canal,  and  does  away  with  the  necessity  of  using  a  drill,  at  least,  until 
the  canal  is  large  enough  to  make  drilling  a  safe  procedure. 

The  point  that  I  am  trying  to  develop  is  that  I  believe  that  the  best 
results  are  to  be  obtained  by  eliminating  the  undesirable  or  dangerous, 
and  taking  advantage  of  the  safer  and  desirable  features  and  results,  that 
may  be  obtained  through  the  use  or  application  of  every  chemical  agent 
or  instrument  that  will  meet  the  exigencies  of  the  case  in  hand. 

In  straight  and  sufficiently  open  canals  or  in  canals  that  have  been 
enlarged  by  chemical  means  to  a  sufficient  size  to  pilot  the  root  drill,  for 
the  sake  of  speed,  for  convenience  in  shaping  of  canal,  a  Kerr  drill,  or  a 
Gates-Glidden,  from  which  the  point  has  been  ground,  or  bud  drill,  may 
be  used. 

If  the  finer  canals  contain  fairly  well  organized  pulp  tissue  that  the 
broach  fails  to  engage,  sodium-potassium  should  be  applied.  After  the 
pulp  or  other  organic  tissue  has  been  converted  into  a  soapy  substance, 
the  removal  of  this  soap  from  the  canal  becomes  a  necessity ;  some  of 
it  may  be  removed  with  a  stream  of  water;  only  a  small  proportion,  how- 
ever. Swabbing  with  cotton  on  a  broach  does  but  little  better.  If  the 
root  canals  of  an  extracted  tooth  be  opened  and  thoroughly  treated  with 
sodium-potassium,  the  canals  then  washed  out  with  water  as  would  be 
done  if  the  tooth  were  in  the  mouth,  and  if  you  then  dry  the  tooth  and 
crack  open  the  roots,  in  the  apical  third  or  the  root  canal  a  dark,  rather 
dense,  soapy  mass  will  be  found  packed  within  the  fine  canal.  If  the 
tooth  fragments  be  kept  dry  for  a  day  or  so  the  dentin  will  show  a  green- 
ish yellow  color — not  a  very  pronounced  discoloration,  but  sufficient  to 
show  the  presence  of  a  coloring  matter.  All  of  this  soapy  mass  will  be 
thoroughly  removed  from  the  canal,  if  sulfuric  acid  be  pumped  into  the 
canal  in  sufficient  quantities  to  overcome  the  alkali,  and  having  been 
worked  to  the  end  of  the  canal  with  broach,  then  the  root  canal  be  flooded 
with  a  saturated  solution  of  soda  bicarbonate.  The  reaction  will  at  once 
remove  practically  all  foreign  substance  from  the  canal.  If  the  tooth 
then  be  dried  and  the  roots  cracked  open  the  canals  show  white  and  clean 
as  marble. 

With  the  tantulum  root  excavator  and  sulfuric  acid  the  root  canal 
may  be  enlarged  more  rapidly  and  with  greater  freedom  from  unpleasant 
and  sometimes  dangerous  conditions.  The  acid  destroys  and  breaks  down 
disorganized  organic  tissue,  the  soda  solution  removing  the  debris  without 
forcing  the  disorganized  substance  through  an  open  foramen,  as  many 
dentists  seem  to  fear. 

If  acid  solution  be  placed  in  a  small  glass  tube,  and  you  then  pour 


CANAL   SURGERY  AND    ORAL  INFECTION 


483 


the  soda  solution  into  the  tube,  it  will  be  seen  that  chemical  action  is  all 
on  top  of  the  acid,  or  only  on  the  surface  of  acid  exposed  to  the  soda; 
or,  in  other  words,  it  does  not  react  in  the  form  of  an  explosion,  the 


Fig.  499.  Copper  band  cemented  on  tooth  to 
facilitate  the  placing  of  rubber  dam  where 
the  cavity  extends  below  the  gum  margin. 


Fig.   500. 


Showing  curvature   of   buccal   roots 
of  upper  molar. 


larger  end  of  the  canal  being  open  and  offering  no  resistance  to  the  gas. 
If  the  acid  solution  should  pass  through  the  foramen  no  further  reaction 
could  take  place  than  that  of  irritation,  as  is  shown  in  Fig.  505. 


Fig.  501.  Shows  amount  of  tooth  structure  to 
be  removed  to  get  as  nearly  as  possible  in  a 
straight  line   with  the   foramen. 


Fig.  502. 


Showing  curvature  of  roots  of 
lower    molar. 


484 


APPENDIX 


Fig.  504.  Transverse  sections  of  large  flat 
root.  A.  Canal  filled  with  disorganized  prilp 
tissue.  B.  Attempt  to  clean  canal  with 
drills  and  broaches  often  digs  a  passageway 
through  the  disorganized  canal  contents.  C. 
By  chemical  methods  everj  vestige  of  or- 
ganic tissue  may  be  removed. 


Fig.  505.  B.  Self-limiting  action  of  sulphuric 
acid  solution  on  cancelous  bone  tissue.  A. 
Action   of  sodium   potassium   on   same   bone. 


Fig.  506,     $pme  itijitrHments  used  for  the  opening  of  root  canals. 


CANAL  SURGERY  AND    ORAL  INFECTION  485 

Root  Canals  Tilling. 


By  Dr.  J.  R.   Callahan,  Cincinnati,  Ohio 


Colophony,  resin,  commonly  known  as  rosin,  is  obtained  from  tur- 
pentine by  distillation.  In  the  process  the  oil  of  turpentine  comes  over 
and  the  rosin  remains  behind.  Rosin  varies  in  color  from  dark  red-brown 
to  black  and  white,  according  to  its  purity,  and  the  degree  of  heat  used 
in  its  preparation.  Chemically,  it  is  the  anhydrid  of  abietic  acid.  It  has 
the  physical  and  chemical  properties  common  to  all  rosins.  It  softens 
at  176  degrees  F.  and  fuses  completely  at  275  degrees  F.,  is  insoluble  in 
water;  with  difficulty  is  soluble  in  alcohol;  freely  soluble  in  chloroform, 
acetone,  benzone,  and  fatty  oils. 

The  rosin  that  is  best  adapted  to  dental  uses  that  I  have  been  able 
to  find  is  that  prepared  by  Barnardel  for  the  use  of  the  violinist.  It  is 
a  French  preparation,  very  near  the  color  of  dentin.  The  formula,  as 
given  below,  makes  a  very  thin  solution.  It  required  a  long  time  for  me 
to  realize  the  advantage  in  the  use  of  a  thin  solution.  A  thick  mixture 
will  not  pentrate  the  tubules,  nor  does  it  give  up  enough  chloroform  to 
dissolve  the  gutta-percha : 

^     Rosin gr.  xii 

Chloroform oiij 

n^     Ft.  sol. 

As  we   are  to   deal  with   dentin  that  has  been 

Httatomvof  subjected  to  infection,  a  brief  rehearsal  of  the  his- 

DentilU  tological  anatomy  of  dentin  will  aid  us  in  getting 

our  mental  eyes  in  the  same  focus. 

Arthur  Hopewell  Smith,  in  his  late  book,  "  An  Introduction  to  Dental 
Anatomy  and  Physiology,"  says : 

"  The  functions  of  dentin  are  to  give  substance  to  the  tooth  itself ; 
to  provide  a  centre  of  sensation ;  to  protect  the  pulp.  Enamel  is  without 
the  pale  of  nutrition.  The  pulp  is  highly  vitalized  and  the  dentin  is  on 
the  borderline  of  the  living  and  the  dead :  semi-vitalized,  if  one  may  so 
speak. 

"  Nature  would  not  for  a  moment  tolerate  the  presence  in  the  midst 
of  living  tissues  of  a  dead  body  like  enamel.  The  result  is  therefore  the 
presence  between  the  living  pulp  and  the  inert  enamel,  of  a  large  area, 
relatively  speaking,  of  a  tissue  which  is  marvelous  and  unique.  In  no 
other  part  of  the  body  do  we  find  an  entirely  tubular  structure  like  dentin. 
Its  peripheral  parts  where  it  joins  the  inorganic  enamel  and  cementum 


486  APPENDIX 

are  less  vitalized  than  in  central  parts.  This  explains  the  reason  why 
the  dental  tubules  are  not  of  the  same  caliber  throughout  their  lengths. 
They  vary  from  1.7  to  5  m.  The  diameter  of  the  tube  diminishes  as 
it  proceeds  outward,  until  at  the  peripheral  region  of  the  tooth  it  becomes 
immeasurable.  The  dentin  of  the  crown  of  teeth  is  more  plentifully 
supplied  with  living  material  (protoplasm)  than  the  roots;  hence  the 
tubes  branch  more  frequently  in  the  latter  than  in  the  former  situation. 
The  tubes  carry  the  dentinal  fibrils;  that  is,  the  peripheral  poles  of  the 
odontoblasts." 

It  is  through  these  dentinal  fibrils  that  nervous  stimuli  are  trans- 
mitted to  the  pulp.  Following  the  teachings  of  Miller  and  Black  in  the 
study  of  carious  dentin,  we  note  among  other  interesting  things  that 
caries  progress  along' the  lines  of  the  dentinal  tubuli;  that  the  form  of 
the  disintegrated  dentin  is  that  of  a  cone  with  the  apex  toward  the  pulp 
chamber,  and  that  the  dentin  is  decalcified  in  advance  of  the  penetration 
of  the  micro-organisms. 

It  is  not  likely  that  in  the  preparation  of  cavities  we  always  remove 
the  apex  of  the  affected  dentin.  In  deep-seated  cavities  is  this  advisable  ? 
In  spite  of  the  application  of  strong  antiseptic  agents,  recurrent  decay 
may  develop  and  toxins  finally  reach  the  pulp. 

If  the  remaining  traces  of  thin  layers  of  decayed 

TIdvantaacs  dentin  can  be  thoroughly  dehydrated,  the  application 

of  Rosin.  of  rosin  solution  may  be  of  great  service. 

First,  rosin  being  more  or  less  a  non-conductor, 
it  reduces  the  shock  of  thermal  changes. 

We  are  taught  that  the  decalcified  dentin  that  is  to  be  found  just  in 
advance  of  the  micro-organisms  in  carious  dentin  furnishes  food  for  the 
invading  germs.  If  the  remaining  decalcified  dentin  be  saturated  with 
rosin,  I  imagine  the  cost  of  living  in  that  region  will  become  prohibitive. 
However,  if  the  rosin  solution  reaches  the  farthest  boundaries  of  the 
decalcified  dentin  through  the  infected  area,  then  the  micro-organisms 
within  the  tubuli  will  have  been  engulfed  within  the  rosin  solution,  and 
unless  the  bacteria  are  able  to  liquify  the  rosin,  they  will  be  forever 
inhibited  from  further  activity,  be  they  aerobic  or  anaerobic,  in  active  or 
spore  form.  I  need  only  mention  the  antiseptic  properties  of  the  chloro- 
form. 

This,  you  will  admit,  would  be  a  very  desirable  condition  in  which 
to  have  a  layer  of  decayed  or  decalcified  dentin  over  the  pulp,  where  the 
removal  of  the  layer  of  decay  would  mean  the  exposure  of  the  pulp. 

The  most  satisfactory  results  that  I  have  had  in  capping  pulps  has 


CANAL   SURGERY  AND    ORAL   INFECTION  487 

been  a  flow  of  rosin  solution  over  the  exposure,  evaporating  the  chloro- 
form with  warm  air,  then  to  cause  a  very  thin  cement  to  flow  over  the 
floor  of  the  cavity  and  the  thin  coat  of  rosin  and  allow  it  to  harden,  being 
very  careful  to  avoid  pressure  of  any  kind  on  the  cement  until  quite  hard. 
This  practice  has  been  confined  to  quite  small  and  recent  exposures. 
Not  the  least  satisfactory  use  of  the  rosin  solution  is  after  more  or  less 
thorough  drying  of  the  cavity  and  application  of  the  rosin  prior  to  the 
insertion  of  gutta-percha  filling,  either  as  a  temporary  or  permanent  filling. 
On  the  removal  of  a  temporary  stopping  of  this  nature,  that  has  been 
in  place  a  week  or  a  month,  the  decayed  dentin,  which  for  any  reason 
may  have  been  left  in  the  cavity,  will  be  found  noticeably  tough  and  hard 
and  dry,  due  to  the  presence  of  the  rosin,  and  the  sensibility  of  the  dentin 
will  be  materially  less,  showing  that  the  dentin  has  been  free  from  the 
irritating  efifects  of  acids,  or,  in  other  words,  the  fibrils  have  been  in  a 
state  of  comparative  rest.  And  after  all  is  said,  the  chief  function  of  the 
surgeon  is  to  remove  the  irritant  and  place  the  affected  region  at  rest,  to 
the  end  that  Nature  may  perform  a  cure. 

We  now  come  to  the  consideration  of  the  time- 
Koof  Cfintll  worn  subject  of  root-canal  filling. 

Tilling*  If  possible,  is  it  desirable  or  necessary  that  the 

tubuli  be  sealed? 
Dr.  Hermann  Prinz,  whom  I  regard  as  one  of  the  foremost  among 
our  scientific  research  workers,  said  in  a  paper  read  before  the  St.  Louis 
Dental  Society,  September  2,  1912:  "  If  the  canal  is  not  filled  perfectly, 
serum  will  seep  into  it  from  the  apical  tissues.  The  serum  furnishes 
nutrient  material  for  the  micro-organisms  present  in  the  tubuli  of  a 
primarily  infected  root  canal." 

The  dentin  is  traversed  by  dentinal  tubuli,  which 
multivk  number  from  25,000  to  30,000  to  the  square  niilli- 

Torsmin^l.  meter.      The   pulp   in   situ   sends   protoplasmic   pro- 

cesses into  these  tubuli,  and  is  connected  with  the 
peripheral  tissues  by  arteries,  veins  and  nerves  which  pass  through  the 
main  foramen  and  a  number  of  small  foramina  (usually  2-7)  present 
in  the  apex  of  the  tooth.  According  to  Fischer,  these  accessory  foramina 
are  found  in  about  ninety  per  cent,  of  all  permanent  teeth.  These  anotomic 
facts  are  not  sufllciently  emphasized  at  present.  Their  significance  is  of 
great  importance  for  the  full  comprehension  of  the  pathology  of  sec- 
ondary infection. 

In  an  incipiently  infected  root  canal,  these  dentinal  tubuli  and  the 
small  foramina  offer  ready  hiding-places  for  various  forms  of  pathogenic 
bacteria. 


488  APPENDIX 

After  exhausting  the  nutrient  material,  the  bac- 
flCtion  Of  teria    become    attenuated,    or    they    assume    resting 

Bacteria.  forms.     If  the  tubuh  and  the  foramina  are  tightly 

sealed,  these  enclosed  bacteria  must  necessarily  re- 
main permanently  confined  in  their  lodging  places,  while  if  the  root  canal 
filling  leaks,  the  seepage  of  serum  furnishes  fresh  material  which  offers 
excellent  opportunity  for  their  renewed  activities. 

By  continuity  this  secondary  infection  spreads  along  the  lines  of 
least  resistance,  i.  e.,  toward  the  apex,  and  finally  reaches  the  pericemen- 
tum. This  tissue  protects  itself  against  the  invading  foe  by  a  reactive 
inflammation,  which  results  in  the  production  of  a  fungus  growth  known 
as  a  granuloma,  or  in  the  past,  as  the  abscess  sack  of  pyogenic  membrane. 
For  years  the  enclosed  bacteria  may  remain  dormant.  At  the  slightest 
provocation,  however,  overexertion,  a  cold,  increased  blood  pressure, 
lowered  vitality,  or  some  other  cause,  they  may  assume  a  most  virulent 
activity,  resulting  in  the  production  of  the  so-called  subacute  abscess. 
Based  upon  this  supposition  we  are  able  to  furnish  a  plausible  explanation 
of  how  these  obscure  secondary  abscesses  occur  about  the  devitalized  teeth 
which  at  one  time  were  pronounced  cured. 

In  one  of  the  most  profound  papers  given  to  the  dental  profession  on 
mouth  infection,  Dr.  Rhein  says :  "  Unfortunately,  as  a  profession  we 
must  admit  that  most  of  the  cases  of  blind  abscess  are  the  results  of  imper- 
fect dental  operations.  In  some  cases  they  may  be  the  result  of  bad  judg- 
ment on  the  part  of  the  operator ;  in  others  they  may  be  due  to  ignorance 
and  incompetence,  but  a  very  large  number  of  cases  are  attributable  to 
the  failure  of  the  educated  dentist  to  give  the  time  needed  to  perform  an 
aseptic  operation  and  have  the  field  absolutely  free  from  the  possibility 
of  future  infection.  This  is  absolutely  nothing  short  of  malpractice  when 
done  by  a  dentist  who  knows." 

We  have  the  testimony  of  several  investigators  to  the  effect  that  it 
is  possible  to  sterilize  the  root  canal  proper,  but  it  is  an  impossibility  to 
sterilize  the  infected  dentin  of  a  tooth  while  it  remains  in  the  mouth. 

The  microscope  and  the  culture  media  have  shown  us  conclusively 
that  we  have  been,  and  are  now,  leaving  enormous  numbers  of  micro- 
organisms v/ithin  the  body  with  a  more  or  less  available  route  open  to 
the  circulatory  system  where  they  may  reach  any  part  of  the  body,  carry- 
ing destruction  to  those  organs  or  parts  that  may  offer  the  most  attractive 
lodging  place. 

A  most  significant  fact  must  be  borne  in  mind  in  regard  to  the  devi- 
talized dentin.  We  have  no  blood  current  to  assist  in  the  struggle.  The 
dentin  has  aboslutely  no  power  even  to  assist  in  repair.     No  granulation 


CANAL   SURGERY  AND    ORAL   INFECTION  489 

nor  scar  tissue — nothing  but  an  inert  tubular  mass  infected  by  millions  of 
toxin-producing  micro-organisms.  We  must  make  of  this  infected  tubular 
mass  an  inert,  harmless  and  stable  body,  including  the  effective  closing 
of  the  numerous  foramina,  to  the  end  that  Nature  may  be  able  to  develop 
the  root  mass  in  a  healthy  and  vigorous  peridental  membrane  that  the  tooth 
may  serve  its  several  useful  purposes  for  a  number  of  years. 

Most  of  us  have  at  one  time  or  another  shared 

_-      -         ^     ,         in  the  opinion  that  v^^hat  the   root   canal  might  be 
Requirements  Of        ^„   ,     .  f  ,111 

Root  Ghm\  nlled  with  mattered  but  little. 

'""•^fl*  The  radiograph  in  the  hands  of  the  advanced 

dental  practitioner  has  brought  to  light  evidence  suf- 
ficient to  prove  the  fallacy  of  such  an  opinion.  It  does  matter  as  to  the 
material ;  it  does  matter  as  to  the  manner  of  placing  the  material  in  the 
canal.  The  matter  of  prime  importance  is  the  sealing  of  the  more  or  less 
numerous  foramina,  and,  as  wq  have  no  assurance  that  all  the  foramina 
in  a  given  root  canal  are  located  near  the  apex,  it  becomes  our  duty  to 
seal  the  whole  length  of  each  canal  with  a  material  that  will  search  out 
and  seal  minute  canals  or  openings  which,  owing  to  physical  conditions, 
we  are  unable  to  see. 

Have  we  a  root  canal  filling  material  that  will 
Gtltta-Percba  meet  the  requirements  indicated  above?     We  have 

KOOt  THlingS.  three    that   may   be    considered.      Gutta-percha    and 

chloro-percha  in  combination ;  paraffin,  as  advocated 
by  Dr.  Hermann  Prinz  and  Dr.  Dunning,  and  the  combination  of  rosin 
and  gutta-percha.  With  the  gutta-percha  cone  and  chloro-percha  you 
are  quite  familiar.  We  know  of  many  successes  as  well  as  of  the  many 
unhappy  failures  with  this  root  filling,  sometimes  due  to  faulty  manipula- 
tion, but  often  due  to  the  fact  that  the  root  canal  filling  has  shrunken 
sufficiently  to  admit  body  fluids  to  the  canal,  or  permit  egress  of  the 
micro-organisms  that  infested  the  tubuli,  and  in  addition  the  gutta-percha 
root  fillings  are  often  found  to  be  saturated  with  decomposed  and  odor- 
iferous substances  that  we  are  altogether  too  familiar  with. 

The  paraffin  root  canal  filling,  as  advocated  by 
Paraffin  ^^-    Prinz   and    Dr.    Dunning,    has   many   attractive 

KOOtTilHngs,  features,  and  time  may  prove  it  a  most,  if  not  the 

most  acceptable  root  filling.  I  have  not  always  suc- 
ceeded in  getting  the  paraffin  to  the  apex  of  the  roots  of  upper  teeth.  If 
the  wire  is  too  hot  the  paraffin  will  collect  about  the  shank  of  the  instru- 
ment, and  if  not  hot  enough  it  does  not  flow  to  all  parts  of  the  canal. 
The  melted  paraffin  will,  however,  follow  the  paraffin  oil  into  the  tubuli 


490  APPENDIX 

and  foramina  if  treated  porperly.  It  will  take  time  to  prove  its  perma- 
nence with  the  body.  Our  previous  experiences  and  the  experiences  of 
the  surgeon  have  made  us  a  litle  shy  on  this  point. 

The  technic  of  the  rosin-gutta-percha  root  filling 

Rosin  and  ^^  simple,  easy,  quick,  and  sure  to  seal  all  tubuli  and 

Gutta-Pcrcfta  foramina  that  are  open.     Before  proceeding  with  the 

Root  Tiilings.  filling  of  the  root  canal,  all  instruments,  cotton-paper 

points,  gutta-percha  points,  should  be  placed  in  the 

steam  chest,  superheated  steam  being  the  most  effective  sterilizing  agent. 

After  steaming  the  proper  length  of  time,  the  steam  is  shut  off  from  the 

chest.     This  soon  dries  the  instruments  and  points  and  cotton  broaches. 

The  gutta-percha  and  paper  points  after  cooling  in  the  basket  have  lost 

none  of  their  desirable  properties. 

I  have  said  that  a  root  canal  should  be  of  the  general  shape  of  the 
fine  paper  root  canal  driers  as  furnished  us  by  the  dealers.  In  addition 
to  this  general  form,  have  the  mouth  of  each  canal  a  decided  saucer  shape. 
This  will  facilitate  the  placing  of  agents  or  instruments  to  or  near  the 
apical  foramen. 

The  first  step,  then,  is  the  complete  dehydration 

DfViltfl  °^  ^^^  dentin,  using  acetone,  as  advised  by  Dr.  Prinz, 

0(inaK  as  the  dehydrating  agent.     After  flooding  the  canal 

with  acetone,  use  the  paper  points  liberally  until  the 

canal  is  entirely  free  of  moisture.     Follow  this  with  warm  air.     Then 

hold  a  warm  wire  in  the  canal  for  a  minute  or  two,  being  careful  that 

the  wire  is  not  hot  enough  to  scar  any  part  of  the  canal. 

Right  here  is  where  many  root-canal  operations  fail.  The  canals 
and  tubuli  must  be  as  dry  as  it  is  possible  to  make  them,  bearing  in  mind 
that  it  is  possible  to  do  damage  by  overheating  the  root. 

Now  flood  the  dry  root  canal  with  the  thin  rosin 
TntrodUCina  solution,  pumping  it  in  with  a  wisp  of  cotton  on  a 

Rosin.  broach.     When  the  canal  is  full  of  the  solution,  pass 

a  fine  wire  or  broach  to  the  end  of  the  canal.  Work 
out  all  of  the  air  that  may  be  trapped  therein.  This  is  of  vital  importance. 
After  the  canal  has  been  flooded  or  pumped  full  of  the  rosin  solu- 
tion, dip  the  cotton  and  broach  that  is  being  used  into  or  pick  up  on  the 
cotton,  bismuth  oxide  hydrate.  Work  this  into  the  rosin  solution  that  is 
already  in  the  canal.  This  is  not  essential  to  the  preservation  of  the  fill- 
ing, but  makes  a  more  distinct  picture  of  the  finer  canal  fillings  when  the 
X-ray  is  in  use. 


CANAL   SURGERY  AND    ORAL   INFECTION  491 

The  canal  point  should  be  made  of  the  base  plate 
_        .  gutta-percha.    It  should  carry  no  drugs  nor  any  addi- 

CiUttJI-Pcrcba  tional  element  that  will  have  a  tendency  to  weaken 

^^^^*  or  reduce  the  strength  or  rigidity  of  the  cone,  because 

we  wish  the  gutta-percha  to  dissolve  rather  slowly  at 

the  periphery,  while  the  attenuated  centre  retains  rigidity  sufficiently  to 

permit  of  being  pushed  along. 

Select  a  gutta-percha  cone  that  will  reach  to  or  near  the  end  of  the 
canal,  holding  the  cone  with  a  fine  foil  carrier,  and  pass  the  cone  care- 
fully and  surely  about  half-zvay  into  the  canal,  pumping  the  cone  up  and 
down  in  the  canal,  usually  from  forty  to  sixty  times,  and,  as  it  dissolves 
in  the  chloroform,  advancing  the  cone  farther  toward  the  apex. 

The  pumping  motion  forces  the  rosin  solution  farther  into  every 
opening.  The  chloroform  at  the  same  time  dissolves  the  periphery  of 
the  gutta-percha  cone,  which,  becoming  more  and  more  attentuated,  slips 
farther  toward  the  apex,  surrounding  itself  with  a  mixture  of  gutta- 
percha and  rosin.  The  rosin  seals  the  tubuli  and  at  the  same  time  causes 
the  gutta-percha  to  stick  tight  to  the  canal  walls  and  makes  the  gutta- 
percha more  stable  and  proof  against  the  action  of  body  fluids  or  sub- 
stances. 

If  this  does  not  leave  the  large  end  of  the  gutta-percha  cone  at  or 
near  the  end  of  the  canal,  place  a  small  cone  alongside  or  on  the  first 
one,  then,  with  cold  steel  plugger  points  that  will  go  into  the  canals, 
gently  pack  the  mass  into  the  canal,  using  warm  air  to  soften  the  pro- 
truding gutta-percha  if  necessary. 

This  packing  forces  the  semi-fluid  (chloro-percha  and  rosin)  into 
the  unknown  canals  and  pockets,  and  at  the  same  time  brings  the  surplus 
chloro-percha  to  the  mouth  of  the  canal,  where  it  may  be  taken  up  with 
absorbent  rolls  or  cotton. 

In  multi-rooted  teeth  complete  the  filling  of  each  individual  canal 
before  starting  another. 

Rub  the  steel  plugger  points  on  paraffin  cake  to  prevent  the  partially 
dissolved  gutta-percha  from  adhering  to  the  instrument.  The  pulp  cham- 
ber is  to  be  filled  with  one  of  the  cements. 

You  may  ask :    "  Do  you  succeed  in  filling  all 

Queries  canals  and  tubuli  to  the  farthest  extremity  ?  "     No ; 

J1n$wered«  only  those   that  are   open   and   dry  to   the   farthest 

extremity. 
Are  we  likely  to  have  inflammation  in  the  periapical  region  following 
the  closure  of  root  canals  in  this  manner? 

The  probability  of  inflammatory  conditions  in  all  cases  depends  upon 


492  '  APPENDIX 

the  ability  of  the  operator  to  read  the  pathological  signs  of  each  indi- 
vidual case  and  his  skill  and  delicacy  of  touch  in  the  manipulation  of  the 
various  agents  used. 

Rosin  and  chloro-percha  and  gutta-percha  cone  is  superior  to  chloro- 
percha  in  three  ways.  First,  the  rosin  in  chloroform  penetrates  deeply 
into  the  tubuli  and  foramina,  into  which  chloro-percha  will  not  enter  at 
all,  leaving  within  such  tubuli  or  foramina,  upon  the  disappearance  of  the 
chloroform,  a  more  or  less  solid,  inert,  insoluble  substance  that  enmeshes 
the  contents  and  seals  the  lumen  of  such  tubuli  or  foramina.  Second,  the 
rosin  and  chloroform  causes  the  gutta-percha,  in  whatever  form  it  may 
be  applied,  to  adhere  closely  to  the  walls  of  root  canal  or  cavity.  Third, 
the  incorporation  of  the  rosin  in  the  freshly  made  chloro-percha  makes 
an  unshrinkable  and  impervious  mass  about  the  gutta-percha  cone.  If 
gutta-percha  and  rosin  be  dissolved  in  chloroform  and  left  in  an  open 
dish  or  tube  to  dry  or  solidify,  the  rosin  will  rise  to  the  surface  and 
harden  in  a  crust  over  the  gutta-percha.  When  the  mixture  is  made  in 
the  root  canal,  as  has  been  suggested,  the  rosin  in  solution  is  held  firmly 
in  place  in  the  dissolved  gutta-percha  between  the  canal  wall  and  the 
cone  in  the  centre. 

We  must  be  prepared  to  meet  all  sorts  of  morbid  anatomical  changes 
in  the  pulp  chambers,  root  canals  and  the  dentinal  tubuli,  due  largely  to 
constructive  irritations  long  present  in  and  about  the  tooth. 

The  illustrations  I  show  are  selected,  each  one,  to  assist  in  demon- 
strating that  the  teeth  which  require  root  canal  treatment  are,  as  a  rule, 
far  from  being  the  perfect  anatomical  specimens  that  we  see  illustrated 
in  our  text-books.  A  tooth  that  has  lost  its  pulp  has  usually  been  sub- 
jected for  a  long  time  to  those  conditions  that  bring  about  destructive  as 
well  as  constructive  changes. 

The  rosin  solution  does  not  show  in  X-ray  pictures  until  mixed  with 
gutta-percha,  when  it  shows  very  plainly  in  the  canals  and  foramina,  but 
not  in  the  tubuli.  Chloro-percha  will  not  enter  the  tubules ;  bismuth 
oxide  does  not  dissolve  in  chloroform,  and  therefore  does  not  enter  the 
tubuli ;  the  blue  stain  spoken  of  enters  the  tubuli  with  the  chloroform  and 
rosin  solution,  but  does  not  show  in  X-ray  pictures ;  so,  in  order  that  we 
might  have  some  visible  evidence  of  the  dififusibihty  of  the  rosin  solution 
through  the  dentin,  I  have  resorted  to  color  photography.  To  vouch  for 
the  correctness  of  the  pictures  I  have  the  original  specimens  here  for 
comparison.  One  better  versed  than  I  in  laboratory  technic  could  cer- 
tainly work  out  a  more  satisfactory  scheme  than  this. 

The  pulp  canals  of  a  number  of  extracted  teeth  were  opened 
mechanically — that  is,  with  burs  and  drills — dehydrated  and  pumped  full 


CANAL  SURGERY  AND    ORAL   INFECTION 


493 


of  the  rosin  and  chloroform  that  had  been  stained  blue.  Then  the  gutta- 
percha cones  were  used  as  has  been  described  above. 

I  do  not  claim  that  this  procedure  gives  an  exact  reproduction  of 
conditions  in  a  tooth  canal  while  the  tooth  is  yet  in  service  in  the  mouth. 
I  do  claim  that  the  specimens  and  the  pictures  give  a  clear  and  under- 
standable basis  from  which  we  can  work  toward  a  reasonable  ideal. 

The  illustrations  following  are  shown  more  to  explain  the  theory 
than  to  prove  results.  There  is  a  vast  difference  between  filling  a  root 
canal  in  an  extracted  tooth  and  one  in  situ. 


Fig.  507.     Water  dropped  into  a  dry  glass  tube  does  not  go  to  the  end  of  the  tube  on  account  of 
entrapped  air.     Rosin  solution  should  be  worked  to  the  ends  of  root  canals  with  fine  broach 


Fig.  508.  Shows  what  happens  when  long 
gutta-percha  canal  point  is  forced  into  c^nal 
without  the  pumping  motion 


Fig.   509. 
(See  caption  under  Fig.  ,t;ioli 


494 


APPENDIX 


Figs.  509  and  510.  Tooth  substance  having 
been  dissolved  away  from  root  canal  filling. 
Shows  the  long  minute  canals  that  the 
rosin  and  gutta-percha  solution  enters  and 
seals. 


Fig.  511.  Palatine  root  of  upper  molar  en- 
larged with  drill,  making  a  false  pocket. 
The  rosin-gutta-percha  solution  not  only 
filled  the  false  pocket,  but  entered  the  true 
canal  and  filled  it  to  the  end. 


Fig.  512. 


The  shaded  area  about  the  root  canal  filling  shows  the  distance  that  the  rosin  has 
penetrated  the  dentinal  tubuli  in  this  tooth  root. 


CANAL   SURGERY   AND    ORAL   INFECTION  495 

Devitalization  of  the  Pulps  of  l)ealtby  Ceetb  Tor  Briage  mork 

Until  recently  the  writer  has  been  a  sincere  advocate  of  devitaliza- 
tion of  teeth  to  be  shell-crowned  for  bridge  abutments,  and  it  is  still 
my  opinion  that  if  a  tooth  is  properly  prepared  to  receive  the  ordinary 
type  of  shell  crown  the  tooth  will  be  so  mutilated  that  the  pulp  in  it  will 
die.  A  new  type  of  shell  crown  then,  the  use  of  which  does  not  necessi- 
tate such  destruction  of  tooth  structure  as  to  endanger  the  vitality  of  the 
pulp,  is  a  thing  I  receive  with  great  gratitude. 

It  is  fortunate  that  I  am  able  to  print  the  following  excellent  paper 
by  Dr.  D.  A.  House.  I  wish  to  say  to  readers  who  may  not  appreciate  the 
value  and  importance  of  Dr.  House's  paper,  that  Dr.  House  demonstrated 
the  making  of  the  crown  he  describes  to  me  several  years  ago,  and  I  paid 
little  attention  to  him.  Do  not  make  the  mistake  of  inattention  I  made. 
Every  dentist  should  make  crowns  such  as  Dr.  House  describes.  What 
folly  it  is  to  extract  one  abscessed  tooth  and  then  devitalize  two  teeth, 
fill  the  canals  imperfectly,  and  insert  a  bridge ! 


J{  metboa  for  makind  a  aold  €rown  for  Bndgework  without  Pulp 

Devitalization. 

D.  A.  House,  D.D.S.,  Indianapolis 

Ever  striving  toward  accuracy  and  perfection  to  meet  new  condi- 
tions constantly  arising,  the  dental  profession  has  to  cope  at  present  with 
facts  which,  a  few  years  ago,  were  neither  heard  of  nor  anticipated. 

Scientific  and  clinical  research,  coupled  with  Roentgenology,  have 
proved  that  foci  of  infection  exist  in  the  dental  field  and  not  only  do 
exist  there  but,  too  often,  are  there  because  of  faulty  dental  operations. 
This  naturally  places  the  dental  profession  in  a  rather  precarious  position. 

Scientific  research  has  quite  conclusively  proved  that  neuritis,  arthri- 
tis, endocarditis,  &c.,  &c.,  can  be,  and  are,  caused  by  infection  being  ad- 
mitted into  the  blood  stream.  That  there  is  somewhere  a  focus  where 
the  infection  is  produced  and  that  that  focus  of  infection  may  exist  at 
the  apex  of  the  root  of  a  devitalized  tooth.  The  lesion  about  the  tooth 
may  not  be  manifested  in  any  way  whatever.  The  tooth  may  not  ever  be 
suspected  of  being  in  any  condition  other  than  normal ;  and  yet  it  may  be 
the  prime  source  of  any  one  of  numerous  conditions  that  make  life  miser- 
able for  the  patient  and  can  even  destroy  life  itself. 

With  the  aid  of  the  radiograph  these  foci  of  infection  are  not  only 


496 


APPENDIX 


revealed  to  us  almost  unfailingly,  but  it  reveals  to  us  the  cause  of  the 
infection,  and  embarrassing  as  it  is  to  admit  it,  the  dental  profession  must 
acknowledge  it  is  often  due  to  faulty  and  unjudicious  operations. 

If  then,  the  above  conditions  do  exist,  and  are  caused  to  exist  by 
faulty  technic  or  impossible  perfection  in  operation,  the  logical  procedure 
is  to  do  the  operation  in  a  manner  by  which  the  faulty  or  impossible 
feature  is  eliminated. 

When  a  shell  crown  is  indicated  in  the  construction  of  a  bridge,  in- 
stead of  pulp  devitalization  in  order  to  prepare  the  natural  tooth  crown 
in  such  a  manner  that  the  crown  band  may  be  adjusted  as  accurately  as 
possible  around  the  cervix  of  the  tooth,  which  is  practically  impossible  to 
do  accurately  enough  to  prevent  subsequent  irritation  of  the  gingivae,  I 
have  adopted  the  following  technic  for  crown  construction.    This  method 


Fig.    513. 


Fig.    514. 

not  only  eliminates  pulp  removal  with  is  dangerous  sequalae  but  leaves 
the  gum  tissue  in  its  natural  normal  condition,  instead  of  producing  a 
condition  conductive  to  disease. 

Having  noted  the  results  of  this  form  of  crown  construction  for  a 
number  of  years,  I  use  it  exclusively  where  the  shell  crown  is  indicated 
for  bridge  abutments,  not  only  on  molars  but  bicuspids,  also  where 
esthetic  considerations  do  not  contraindicate  its  use.  The  technic  being 
similar  in  either  case,  I  will  illustrate  it  in  the  construction  of  the  molar 
crown  only. 

The  normal  form  of  a  molar  or  bicuspid  naturally  makes  the  entire 
circumference  convex.     Because  of  this  convexity,  the  diameter  differs 


CANAL  SURGERY  AND  ORAL  INFECTION 


497 


from  the  occlusal  surface  to  the  cervix  (Fig.  513).  In  order  to  retain  an 
anatomical  form  of  the  crown  when  completed,  and  to  have  it  sufficiently 
heavy  for  rigidity,  it  is  necessary  to  grind  the  natural  tooth  to  a  point 


Fig.   517. 


Fig.  519. 


Fig.  518. 


^S»»*~««8S8^ 


Fig.  520. 


about  midway  between  its  greatest  diameter  and  the  gingival  margin. 
(Fig.  514.) 

There  is  seldom  any  discomfort  to  the  patient  as  the  enamel  is  only 
partially  removed.  Care  should  be  taken  not  to  injure  the  contact  point  of 
the  approximating  tooth. 


498 


APPENDIX 


Having  ground  the  tooth  conical  in  form,  an  impression  is  taken, 
model  made  and  a  pure  gold,  34  gauge,  band  fitted  to  the  model  in  the  fol- 
lowing manner:  A  piece  of  gold  curved  in  form  like  Fig.  515,  either 
by  cutting  or  passing  a  straight  piece  through  the  gold  roller  with  one 
set  screw  advanced  a  little  closer  than  the  other,  when  formed  into  a  band 
will  be  conical  in  shape  (Fig.  516),  and  is  fitted  to  the  model  closely  and 


Fig.  521. 


Fig.  522. 


Fig.    523. 


made  to  extend  just  to  the  point  where  the  tooth  has  been  ground  (Fig. 
517).  After  being  fitted  to  the  model,  it  is  fitted  on  the  tooth  in  the 
mouth.  Be  sure  to  extend  it  to  all  points  where  the  enamel  has  been  re- 
moved. It  should  be  made  to  fit  the  tooth  perfectly  by  burnishing,  and 
the  occlusal  end  should  be  short  enough  not  to  interfere  with  the  closing 
of  the  teeth. 

It  is  removed  in  a  plaster  impression  and  before  pouring  the  model 
a  little  baseplate  wax  is  flowed  on  the  inner  surface  of  the  band,  so  later, 
by  slightly  warming  it,  it  is  easily  removed  from  the  model. 

With  the  band  in  its  proper  position  on  the  model,  a  second  band  of 
29  or  30  gauge,  22-K.  gold  is  contoured  and  fitted  over  the  first  band. 
Fig.  518,  noting  especially  the  original  contour  and  contact  point  of  the 


CANAL   SURGERY  AND    ORAL   INFECTION  499 

natural  tooth.  The  second  band  should  be  about  1/32  of  an  inch  shorter 
at  the  cervical  margin  than  the  first  band,  so  that  after  uniting  the  two 
with  22-K.  solder  the  cervical  end  may  be  finished  to  a  sharp  edge  to  pre- 
vent any  thick  margins  and  to  facilitate  possible  future  burnishing. 

The  space  between  the  bands  having  been  perfectly  filled  with  solder, 
it  is  now  ready  for  final  adjustment  to  the  tooth.  The  occlusal  surface 
of  the  tooth  having  been  ground  sufficient  for  a  heavy  occlusal  surface 
on  the  crown  (Fig.  519),  the  band  is  trimmed  just  even  with  the  occlusal 
plane.  A  piece  of  pure  gold,  34  gauge,  is  soldered  on  the  end  of  the  band, 
which  is  then  placed  on  the  tooth.  The  pure  gold  end  is  now  burnished 
to  the  ground  occlusal  surface  of  the  tooth. 

A  wafer  of  softened  inlay  wax  (Fig.  520)  is  then  placed  on  the 
occlusal  surface  of  the  crown  and  the  patient  instructed  to  "bite."  After 
the  wax  is  chilled,  the  band  and  wax  are  removed,  the  wax  securely  at- 
tached and  carved  (Fig.  521).  Next  invest  and  cast.  Should  the  casting 
form  an  imperfect  attachment  to  the  crown,  unite  the  parts  with  solder. 

This  part  of  the  technic  being  completed,  it  is  ready  for  replacement 
on  the  tooth  (Fig.  522)  for  final  impression  and  subsequent  finishing  of 
the  bridge  in  whatever  manner  appeals  to  the  operator. 

While  this  form  of  crown  construction  has  been  most  gratifying 
in  all  cases  where  vital  teeth  are  involved,  I  can  most  heartily  endorse  it 
in  cases  where  a  convergence  of  teeth,  due  to  the  long  loss  of  the  missing 
teeth  (Fig.  523)  has  entirely  changed  their  axial  relations. 

As  I  said  in  a  preceding  paragraph,  this  form  of  crown  construc- 
tion can  be  used  for  bicuspids  when  esthetic  reasons  do  not  interfere ;  it 
can  even  be  carried  to  the  lower  cuspids  under  similar  conditions,  the 
technic  being  similar  in  all  instances. 

For  one  who  prefers  using  the  casting  process  whenever  possible, 
the  technic  can  be  changed  as  follows :  After  the  first  pure  gold  band 
is  fitted,  the  occlusal  end  of  pure  gold  is  soldered  to  this,  the  contour  and 
occlusion  are  formed  in  inlay  wax  and  the  whole  cast  in  one  operation 
instead  of  adding  the  second  band  of  22-K.  gold.  But,  because  of  the 
accurate  fitting  of  the  first  band,  I  find  that  the  shrinkage  following  cast- 
ing is  such  as  to  make  replacement  of  the  crown  on  the  tooth  for  the  final 
impression  more  difficult  than  where  the  double  band  method  is  used. 

In  the  above  method  it  is  not  only  possible  to  construct  a  most 
serviceable  substitnte  for  the  natural  tooth  but  it  is  done  without  sacri- 
ficing the  vitality  of  the  pulps  of  natural  teeth  and  without  jeopardizing 
the  health  and  gum  tissue  and  pericemental  membrane  surrounding  the 
teeth. 


500  APPENDIX 

(Conclusion 

To  conclude  this  chapter,  I  now  quote  from  a  paper  read  before  the 
Chicago  Dental  Society.  As  a  hen  lays  eggs  primarily  "  for  personal  re- 
lief "  rather  than  the  benefit  of  humanity,  I  admit  I  give  the  following 
for  the  same  reason.  I  want  to  advise  physicians,  dentists  and  radiog- 
raphers so  we  may  all  meet  this  problem  of  pulp  canal  work  and  systemic 
infection  to  the  greatest  possible  advantage  of  the  patients  in  our  care : 

To  Physicians* 

1.  Shoulder  your  share  of  the  responsibility  for  the  occurrence  of 
local  foci  of  infection  in  the  mouth. 

2.  Do  not  advise  the  the  extraction  of  two  teeth  because  one  tooth 
is  abscessed — nor  all  teeth  because  some  are  abscessed. 

3.  Never  advise  extraction  without  first  making  radiographs. 

4.  Have  an  expert  read  the  radiographs,  or  pass  on  your  reading, 
until  you  have  become  expert. 

5.  Do  not  say  all  teeth  with  the  pulps  removed  should  be  extracted, 
for  we  do  not  know  that  this  is  true. 

6.  Do  not  forget  that  teeth  have  an  important  function.  This  is  just 
as  much  a  truth  as  it  ever  was.    Keep  it  in  mind. 

7.  Wake  up  to  the  fact  that  to  learn  what  you  should  know  of  this 
subject  you  must  hear  what  dentists  have  to  say  about  it.  Invite  them  to 
lecture  at  your  meetings  and  in  your  schools. 

8.  Keep  this  in  mind :  The  dentists  of  the  United  States  have 
developed  a  Research  Commission,  which  will  rank  with  the  Carnegie  and 
Rockefeller  Laboratories  for  research. 

9.  Remember  that  most  of  the  diseases  of  infancy  were  once  at- 
tributed to  teething. 

To  Dentists 

1.  Do  not  jiggle  about,  and  try  to  sidestep  the  situation. 

2.  Support  the  National  Research  Commission  with  your  heart, 
mind  and  money. 

3.  Let  the  apical  excision  and  curettement  operation  become  a 
common  one,  not  an  uncommon  one. 

4.  Admit  that  the  destruction  of  pulps  has  been  ruthless,  and  as 
you  admit  it,  correct  the  mistake. 

*  August,  1915,  Dental  Review. 


CANAL  SURGERY  AND    ORAL   INFECTION  501 

5.  Develop  a  new  and  better  bridgework,  Bridgework  is  not  to  be 
relegated  to  the  scrap  heap — but  it  should  be  modified. 

6.  Never  expect  to  hear  again  the  man  who  came  to  your  meeting 
and  said  he  "  filled  all  canals  to  the  apex." 

7.  Admit  it  is  impossible  to  reach  and  fill  to  the  apex  all  canals. 
No  man  can  do  it  by  the  methods  you  now  use. 

8.  Look  to  the  National  Research  Commission  to  learn  if  you 
should  extract  teeth  when  it  is  impossible  to  fill  the  canals  to  the  end. 

9.  Know  that  it  is  not  a  crime  to  fail  to  fill  a  canal  perfectly,  but 
that  it  is  a  crime  not  to  try  to  fill  it. 

10.  Charge  for  the  treatment  of  teeth  on  a  time  basis  and  render  a 
bill  whether  you  save  the  teeth  or  not. 

11.  Change  your  slogan  from  "Save  Teeth"  to  "Save  Teeth 
■ — But  Never  At  The  Expense  Of  Producing  A  Chronic  Abscess." 

12.  Do  not  depend  on  medical  men  to  make  and  read  your  radio- 
graphs for  you. 

To  Radiographers 

I.  Do  not  read  a  diagnosis  into  every  radiograph  whether  it  is 
there  or  not.  Learn  to  say,  when  it  is  the  case,  "  The  radiograph  shows 
me  nothing." 

2.  Believe  in  the  infallibility  of  the  radiograph,  knowing  it  is  the 
product  of  definite  and  unchanging  chemical  and  physical  laws,  but 
realize  that,  unless  you  know  these  laws,  it  may  mislead  you. 

3.  Never  deny  the  assertion  that  radiographs  have  unfortunate 
limitations.  Though  the  radiograph  is  the  greatest  single  aid  to  dental 
diagnosis,  it  nevertheless  fails  often  to  show  us  what  we  want  to  see. 

4.  Understand  the  necessity  of  making  more  than  one  radiograph 
of  a  single  case.    When  in  doubt,  verify  with  another  radiograph. 

5.  Distrust  any  radiographic  finding  that  is  not  backed  up  by  the 
clinical  evidence. 

6.  Do  not  profess  to  be  a  dental  radiographer  unless  you  are  a 
dental  pathologist. 

7.  Try  not  to  blame  the  radiograph  for  your  occasional  silly  inter- 
pretations of  it. 

8.  Know  the  list  of  the  common  misinterpretations  of  radiographs. 
(Appendix,  Chapter  VL) 

9.  Understand  that  it  does  not  fall  within  the  province  of  radiog- 
raphers to  be  harsh  critics  of  either  dentists  or  physicians.  Your  position 
is  a  delicate  one.  Handle  it  with  patience,  kindness,  coolness  and  hon- 
esty.   Do  not  try  to  turn  things  upside  down  all  at  once. 


502  APPENDIX 

To  Physicians,  Dentists  and  Radiographers  All! 

Let  tis  all  appreciate  the  necessity  for  team  work.  The  tendency  to 
clannishness  in  the  human  being  is  fundamental.  The  boys  of  the  east 
end  hate  the  boys  of  the  west  end.  Knowing  this  human  fault  of  clan- 
nishness, let  us  guard  against  it. 

When  a  man  of  one  profession  meets  a  bonehead  of  another,  do  not 
attribute  the  osseous  condition  of  the  man's  head  to  the  profession  of 
which  he  is  a  part. 

Let  us  realize  that  to  the  best  of  our  present  knowledge,  if  teeth  are 
properly  treated  they  do  not  abscess. 

Therefore,  they  must  be  treated  properly. 

If  teeth  are  to  be  treated  properly  there  must  be  a  raise  in  the  average 
fee  charged. 

People  turn  from  good  dental  treatment  on  account  of  the  cost,  and 
indeed  and  actually  very  many  of  our  American  people  cannot  afford  to 
have  their  teeth  treated  properly.  What  is  to  become  of  them?  Some 
one  answers,  "  Extract  their  teeth."  The  answer  is  that  the  medical  pro- 
fession has  tried  to  persuade  women  not  to  wear  corsets  ever  since  we 
can  remember,  but  women  wear  them  just  the  same.  Likewise,  it  will 
be  found  impossible  to  induce  poor  people  to  give  up  their  anterior  teeth. 
They  will  go  to  the  dental  quack.  And  what  if  we  expose  the  quack  and 
destroy  him?  It  would  be  a  good,  though  difficult,  thing  to  do,  but  the 
point  is  that  we  do  not  want  to  extract  teeth,  we  want  to  save  them. 

The  solution  of  the  whole  problem  lies,  not  in  the  development  of 
an  inexpensive  method  of  treating  pulp  canals,  which  it  seems  to  me,  is 
impossible,  but  in  a  publicity  campaign  which  will  lessen  the  necessity  for 
treating  canals. 

Do  people  really  know  that  they  save  health,  pain,  money  and  time  by 
having  their  teeth  filled  before  they  ache  ?  In  a  hazy  sort  of  a  way  they 
do ;  but  they  do  not  know  it  well  enough,  and  it  is  our  fault  that  they  do 
not.     We  must  teach  them. 

Our  slogans  are  changing.  We  no  longer  say,  "  Swat  the  fly,"  we 
say,  "  Prevent  the  fly  " ;  we  do  not  say,  "  Reform  the  criminal,"  but  "  Pre- 
vent the  criminal."  We  talk  little  about  "  curing  tuberculosis,"  but  much 
of  "  preventing  it."  So  let  us  not  only  improve  our  pulp  canal  treatment 
work,  but  do  the  bigger  thing — try  to  prevent  the  conditions  which 
make  pulp  canal  work  necessary. 


INDEX 


Abortion 277 

Abscess, 

Alveolar    186 

Chronic   405 

Dentoalveolar    185 

Destruction  of  Tissue  in 

187,  412,  Fig.  452A 

How  to  Avoid 442,  472 

Multirooted    Teeth 190 

Number  of  Teeth  Involved 189 

Of  Crowned  Teeth 191,  452 

Opening  on  Face 253,  257,  419 

Pericemental    195 

Photograph  of 373,  379 

Probable    Causes 472 

Pyorrhea   Alveolaris,   Differential 

Diagnosis    193 

Treatment  of 399,  463 

When    Cured 381,  463,  465 

Absorption  of  Teeth  (See  Resorption) 

A.    C 2,  9,  11,     24 

Acid  Fixing  Bath 78 

Acid,    Sulphuric 479 

Advice  to 

Beginners    in    Radiography    (See 

the    Preface) 128 

Dentists     500 

Physicians    500 

Radiographers     501 

Alopecia     278,  429 

Alternating    Current 2,9,11,     24 

Alveolar  Abscess   (See  Abscess) 

Ammeter   or   Amperemeter 32 

Ampere     4 

Amputation     of     Apex     of     Tooth 

Root    201,  413,  419,  468 

Angle  of   X-rays 99 

Anode     41,  42 

Ankylosis     247,  263 

Anodyne    •  •  447 

Anomalies    230 

Anterior    Palatine    Foramen 364 

Anti-Cathode    41,    42 

Antrum    of    Highmore 234 

Foreign  Body  in 238 

Pus    in 234,  Fig.  451 

Radiographing    of 341 

Apical   Foramen, 

Fining    to 175,  437 

Filling   Through 408,  446 

Multiforamen     439,  473 


Apicoectomy ..201,  413,  419,  468 

Apparatus  Radiographic. ..  .14,  295,  320 

Appendicitis  416 

Aprons,  X-ray  Proof 286 

Armature    9 

Arsenical   Necrosis 231,  422,  472 

Arthritis     416,  456 

Articulation,    Temporo-Mandibular, 

242,  266 

Artificial  Roots 213 

Asepsis 456,  471 

Assistant    Anode ,     46 

Attachment,    Gilmore 375 

Average 

Canal  Filling 438 

Dentist    440 

Azo  Photographic  Printing  Paper..     83 

Bacteremia  416 

Bacteria,    Cultures    of 472 

Bad   Canal   Work 437 

Benoist    Penetrometer 346 

Bi-anodal  X-ray  Tubes 44 

Bismuth   Paste 199 

Blood    Supply. 266 

Bone    Eburnation 382 

Bone    Regeneration... 203,  381,  400,  465 

Bone    "Whorls" 214 

Boxes,    View 136,  406 

Bridgework    209 

On  Vital  Teeth 498 

Bromide    Paper 347 

Broken 

Broach  in   Canal 205 

Tooth    ......205,  208 

Burn,  X-ray   (See  Dermatitis) 

Cabinet,   Protective   Lead 280 

Calculus    194,  217 

Callahan 

Papers    by 474 

Solution    485 

Technic  for  Canal  Filling 485 

Canal  Filling, 

After-pain   447 

Average    438 

Asepsis    vs.     Mechanical    Perfec- 
tion  383,  456 

Callahan's    Solution 485 

Causes  of  Failure 458 

Chart  of 438.  452 


Difficulty  437 

Economics   453 

Encapsulating    Apex 446 

Failures    437 

Gutta    Percha 267 

In    Molars 458 

In    Teeth    Other   than   Molars...  437 

Kinds  Seen  in  Radiographs 408 

Materials   401 

Muhiforamen  439,  473 

Preparation    for 474 

Proprietary,   Pastes 401 

Radiography  of .  ! 370,  447 

Repeated    Efforts 439 

Rosin    Solution 485 

Technic    485 

To   Apex 175,  437 

Through  Apical  Foramen 408,  446 

What  Is  Bad 447 

Canals  of  Teeth, 

Enlarging 175,  210,  460  474 

Filling    175,  485 

Canal  Surgery   (See  Canal  Filling) 

Cancellous  Spots  in  Bone Fig.  401 

Cancer 274 

Carelessness  with  X-rays 426 

Caries, 

Dental    269,  420 

Of    Bone 231 

Cathode  42 

Collars    2)2)7 

Stream    48,  49,  331 

Cement 403 

Cementoma    214,  Fig.  431 

Chair,   Radiographic 112 

Charts, 

Conditions  Indicating  Extraction.   415 

Dr.  Best's 472 

Educational  452 

Evidence  of   Infection 410 

Ionization   470 

Kinds  of  Canal  Fillings 408 

Milliampere-second    355 

Showing  Treatment  Indicated.  .  . .   412 

Cholecystitis    416 

Circuit,    Electric 10 

Coil, 

Faradic    (See   Faradic   Coil). 
High  Frequency    (See  High  Fre- 
quency Coil). 
Induction    (See    Induction    Coil). 
Interrupterless    (See    Interrupter- 
less  Coil). 
Color  of  X-ray  Tube. . .  .51,  52,  326,  332 

Combination  X-ray  Tube 337 

Commutator   9 

Compression       Cones       and       Dia- 
phragms    62),  64,  302 

Condenser   34 

Conductors,    Electric 1 

Congenital  Absence  of  Teeth    (See 
Missing  Teeth), 


Conservation   of    Dental    Pulp.  .442,  495 

Contact   Lantern   Slides 354 

Continuance  of  Infection  After  Ex- 
traction    464 

Converter,   Rotary 36 

Coolidge,  X-ray  Tube 331 

Coronoid    Process Fig.  406 

Cranial   Sinuses 341 

Crooke's    Tube 41 

Crowned  Teeth 181,  191,  452,  495 

Cultures   472 

Culture    Media 472 

Currents    2,     53 

Cut  Outs    (See  Fuses). 

Cutting  of  Teeth,  Delayed 148 

Cycle  2 

Cyst, 

Bone  218 

Dentigerous   222 

Danger, 

Influence  of  Fees 426 

Of   Electric   Currents 430 

Of  the  X-rays 273,  423 

To  Operator 287 

To   Patient 288 

Dark  Room, 

Lantern   68 

Tips  in  Technic 350 

Ventilation   .. : 348 

D.  C 2,  9,  11,   19,  295 

Death  from  X-rays 275,  276 

Deciduous   Teeth 157,    161,    162,  163 

Delayed  Eruption  of  Teeth 148 

Densities,  Recorded  on  Radiograph 

136,  138 

Dental  Caries 269,  420 

Dental   Pulp, 

Conservation  for  Bridgework. .  . .   495 

Electric    Test 394,  395 

Test  for  Vitality 394,  395 

Dental   Stereoradiographs 298,  431 

Practical   Value   of 314 

Technic  for  Making 310 

Dental  X-ray  Machines 320 

Denticles 250 

Dentist, 

Advice   to 500 

Average    440 

Educating    445 

Dentoalveolar    Abscess     (See     Ab- 
scess), 

Pain    in 405 

Dermatitis  273,  274,  290,  425 

Developing   Box 129,  134 

Developer   75 

Choice,  of 128 

Hydrochinon    75 

M.   Q 75 

Pyro   76 

Temperature  76 

11 


Development, 

Of   Negatives 74,   128,351 

Of    Prints 83 

Of  Teeth 263 

Destruction    of    Tissue,     Bony    and 
Tooth  187,  415 

Diagnosis    360 

Diagram, 

Cathode    Stream 48 

Compression      Cone      and      Dia- 
phragm       64 

Coolidge   Tube 334 

High   Frequency  Coil 36,  38,     90 

Induction  Coil 20,  32,  33,  34,     86 

Interrupterless   Machine 39,     92 

Mechanical    Interrupter 28 

Pose   for   Radiographs.. 70,   99  to  102 

Pulp   Conservation 442 

Rheostat    25 

Shunt   45 

Stereoscopic    Work 302 

Switch    22 

Valve  Tube  in  Use 54 

X-rays   48 

X-ray  Tubes 46,     57 

Diaphragms  and  Compression  Cones, 

61,  64,  302 

Differential      Diagnosis,      Pyorrhea 
and  Abscess 193 

Differentiation,    Primary    and    Sec- 
ondary Teeth 161 

Difficulty  of  Canal  Surgery 439 

Direct  Current   2,  9,  11,   19,  295 

Disease,  Systemic 416 

Diseases    of    Eye,    Ear,    Nose    and 
Throat : 416 

Dislocation   of   Condyle 242 

Distance  Between  Target  and  Film 

or   Plate    124 

Distance  Between  X-ray  Tube   and 

Patient    96,     424 

Disto-Buccal   Root  of    Upper    Mo- 
lars     391 

Doctor, 

Best's    Charts 472 

Callahan's    Papers 474 

House's    Paper 495 

Hunter's    Paper 268 

Johnson's    Editorial 357 

Leach's    Film-Holder 116 

Lucas'  Technic 468 

Ottolengui's  Words 407 

Rhein's   Technic 177 

Van   Woert's   Technic. ..  132,    134,  350 

Dose  of  X-rays 288,  424 

Dry    Plates 65 

Drying, 

Immediate    132 

Of    Negatives 80 

Of  Prints 84,     353 

Duration  of  Exposure. 71,  124,  355,     424 

Dynamos     9 


Ear,    Pain   in 228 

Eburnation,    Bone 382 

Economics     1 70,    453 

Editorial,   Dr.   Johnson's 357 

Writer's  Reply 358 

Education, 
In  Radiographic  Work    (See  the 

Preface)    294 

Of    Dentists 445 

Of    Public 441 

Electric  Current,   Danger  ci 430 

Electric  Pulp  Testing, 

Electrophobia    396 

Liability  of  Accident 396 

Limitations    395 

Technic    394,  395 

Electricity  1 

Electrolyte    17,    21 

Electromagnets 7 

Electrophobia    396 

Elementary  Radiography...!   to  85,  319 

Empyema  of   Maxillary   Sinus 234 

Encapsulation  of  Root  End. .  .408,     446 

Endocarditis    416 

Enlarging  Apparatus 433 

Enlargement    433 

Enteritis    416 

Ethmoid   Cells 234,    341 

Evidence    of    Infection    in    Radio- 
graphs, 

Chart  of 411 

Examination  of  Mouth 398,    416 

Example,    Horrible 389 

Exostosis,  Dental 214,  384,    41 1 

Exposure, 

For  Prints 83,     138 

Of  Patient  Time  Limit 288,    424 

Long  with  Big  Outfit 356 

Short  with  Small  Outfit 356 

Time  of,   for  Negatives 71,     124 

Extra-Oral  Radiographs 94,     349 

Extraction   of   Teeth 162,     168 

Chart    Indicating 415 

Continuance  of  Infection  After. .  464 

Few  at  Time 464 

Eye,  Disturbance  of 172,    469 

Facial  Fistula.. 253,  257,    419 

Facial  Neuralgia  (See  Neuralgia). 
Failures  in  Canal  Work,  Causes  of.  458 

Fallibility  of  X-rays 357 

Faraday  8 

Faradic    Coil     (See    Electric    Pulp 

Testing). 
Fatality  from  X-ray  Lesions. .  .275,  276 

Faults  in  Negative 352 

Ferrotype   353 

Field    9 

Filling  (See  Canal  Filling). 

Encroaching  on  Pulp 181,     378 

Large    395 

Filling  Materials  for  Canals 401 


Film, 

Description  of 66 

Methods  of  Holding  in  Mouth...  109 
Mounts   (See  Radiomount) 

Placing  Outside  the  Mouth 349 

Protection  of 297,  346,  350 

Radiographs,  Advantages  of 135 

Special  X-ray 66,  96 

Film    Holders 311 

Ketcham    347 

Kny-Sheerer    305 

Leach  116 

Stereoscopic   435 

Van    Woert 350 

Filter   289,  424 

Fistula  on  Face 253,  257,  419 

Fistulous  Tract 199 

Fixing, 

Box 78 

Of  Negatives 11,  351 

Of    Prints 84 

Fluorescence  of  X-ray  Tubes, 

51,  52,  326,  332 

Fluoroscope    55,  143,  144 

Foot    Switch 427 

Foramen, 

Anterior    Palatine 364 

Mental     363 

Foreign    Bodies 202 

In    Antrum 238 

Fracture, 

Of  Jaw 244 

Of  Tooth 208 

Friedlander's    Shield. 63 

Frontal   Sinuses 234 

Intensifier     344 

Pose   for 341 

Gagging    Ill 

Gastric    Ulcer 416 

Generator  9 

Gilmore    Attachment 375 

Gloves   286 

Granuloma    (See  Abscess) 

Grounding  Electric  Current 120 

Growing    Cultures 472 

Guide  to  Treatment  by  Radiographs 

(Chart)     412 

Gutta  Percha, 

As   Canal   Filling 176,  267 

Non-irritating   176 

Hair,  Loss  of 278,  429 

Headache    260 

High  Frequency  Coil, 

Description    of 33,  322 

Diagram  of 36,  38,  90 

Technic  Involved  in  Use  of. .  .35,  90 

Holder,    Film 311 

Ketcham   347 

Kny-Sheerer    305 

Leach  116 


Stereoscopic 435 

Van   Woert 350 

Holding  Film  in  Mouth 109,  426 

Horrible  Example 389 

Hydrogen   X-ray   Tube 340 

Hydrometer  -21 

Hyoid  Bone 368 

Hypercementosis  (See  Cementoma) 

"Hypo"    ■ 78,    19 

Hypochondriac   261 

Idiopathic    Neuralgia 251 

Ignorance   with   X-rays 426 

Illuminating    Boxes 136,  406 

Immediate  Drying  of  Negative....   132 

Immunity    290 

Impacted  Teeth..  168,  206,  259,  262,  417 
Indication  for  Root  Resection.  .413,  419 

For    Extraction 415 

Induction  Coil, 

Description  of 15,  323 

Diagrams  of 20,  32,  33,  34 

Technic   Involved   in   Use   of....     86 

Infallibility    of    X-rays 358 

Infection, 

About  Third  Molar 418 

Continuance  After  Extraction...  464 
Elimination  Without  Extraction.  463 
Evidence  of,  in  Radiographs. 381,  411 

Local  Foci 272,  399,  462 

Metastatic 272,  416,  456 

Oral  Foci  (See  Local  Foci). 
Periapical    (See  Local   Foci)....  410 

Pyorrheal    464 

Systemic  (See  Metastatic). 

Treatment  of 399,  465 

When  Overcome 400,  465 

Inferior  Dental  Canal 252,  365 

Inflammation   About    Bridge 211 

Inoculation 472 

Insanity   256,  277 

Insomnia 256 

Installation    15,     36 

Insulation    7,     27 

Intensifier    81 

Intensifying   Screens   127,  344 

Interpretation  of  Radiographs. .  136,  357 

Mistakes   in 361 

Interrupterless  Coils, 

Description  of 38,  320 

Radiographs  Made  with '. . .  356 

Technic  Involved  in  Use  of. 92  to    94 

Interrupters   17 

Intra-Oral  Radiographs 94 

Inverse  Current 53 

Inverted   Teeth 172,  173 

Involvment  of    Pulp,   Treatment  to 

Avoid    ...; 442 

lodin.   Treatment   with 466 

Ionization, 

Case    Treated 467 

Chart,    Technic 469,  470 


IV 


Jumping  the  Bite 263 

Kassett    345 

Kilowatt    5 

Kilowatt-Hour    5 

Kinds  of  Canal  Fillings 401,  409 

Lame    Teeth 184 

Lantern   Slides 354 

Large  Plate  Negatives,  Advantages 

of     •  • 135,  392 

Lassitude    278 

Lead  Cabinet 280,  426 

Lead    Screen 280,  296 

Leukemia    277 

Liability   for   Accident 426,  430 

Life,  Loss  of 275 

Lighting  of  X-ray  Tube, 

With   High-Frequency   Coil 91 

With  Induction   Coil 89 

With  Transformer 93,     94 

Limit  of   Exposure 288,  424 

Lingual    Tubercle 369 

Local  Foci  of  Infection. .  .272,  399,  462 

Locked    Jaw 262 

Lower  Anterior  Teeth,  Radiography 

of 112 

Lower     Posterior    Teeth,     Radiog- 
raphy   of 108,  110 

Ludwig's    Angina 253 

Luxation     242 

Machines,  Dental  X-ray 320 

Magnetism   5 

Magneto    9 

Making, 

Crowns  for  Vital  Teeth 495 

Cultures    472 

Dental    Radiographs 65,     85 

Lantern  Slides 354 

Negatives    (See  Negatives). 

Photographic    Prints 83,  353 

Plastic   Radiographs 317 

Radiographs    of    Sinuses 341 

Stereoradiographs    303 

Malformed   Teeth 230 

Malposed   (See  Impacted  Teeth). 

Manufacturers    66,  297,  445 

Mastoid,    Pose   for 344 

Materials,    Canal    Filling 401,485 

Maxillary  Sinus   (See  Antrum). 

Maxillary    Suture 266 

Media.    Culture 472 

Mental    Foramen 363 

Metastatic  Infection 272,  416,  456 

Meters   32 

Methods    of    Holding    Film    in   the 

Mouth     109 

Milliampere  Second, 

Definition    of 355 

Dose  of  X-rays 423 

Exposure    Table 355 


Missing    Molars 151 

Missing    Teeth 148,  156,  157,  266 

Mistakes, 

In   Canal   Filling 458 

In  Interpretation  of  Radiographs  361 

Motor    n 

Moisture,  Protection  of  Film  from, 

97,  350 
Molars, 

Filling    Canals   of 458 

Impacted  Third.  168,  206,  259,  262,  417 

Lower,  Radiography  of 108,  386 

Missing     151 

Upper    Radiography   of 99,390 

Mounts,  Film    (See  Radiomounts) 

Mouth,    Examination    of 398,416 

Myelosarcoma  of  Lower  Jaw 226 

Nasal   Cavity  Spots 365 

Necrosis    231,  365,  368 

Negatives, 

Densities   Recorded  in 136,  407 

Development    of 74,  130,  350,  351 

Drying    of 80,  130,  132 

Faults    in 352 

Fixing    of 11,  351 

Intensification    of 81 

Marking  of 141,  451 

Reducing    of 81 

Scratching    135 

Washing    of 79,  132,  350 

Nephritis    416 

Neuralgia,    Facial  ....  160,  180,  249,  392 

Neurasthenia   256 

Neuritis    416 

Neuroses    256 

New  Standards  in  Canal  Work 440 

New   Words,    Dr.    Ottolcngui's 407 

Non-Conductor 2 

North   Pole  of   Magnet 6 

Nostrils     Fig.  403 

Odontoma     152,  156,  228,  229 

Ohm 3 

Oral  Foci  of  Infection   (See  Local 
Foci). 

Orthodontia 163,  164 

Oscillimeter     54 

Oscilloscope   (See  Oscillimeter). 

Osteology    263 

Osteoma   227 

Osteosclerosis     382 

Overhead   Wiring 327 

Pain, 

After  Canal  Filling 447 

Of  Dentoalveolar  Abscesses 405 

Of  X-ray  Lesions 277 

Palatine    Foramen 364 


Paper, 

Bromide    , 347 

Photographic    83,  347 

Radiographs   on 347 

Parallel  Spark  (See  Terminal  Spark 

Gap)     43 

Patients,  Limit  of  Exposure  for 

288,  424 

Penetration  of  X-rays 56 

Penetrometer    55,  346 

Perforation    of    Teeth 179,  375 

Periapical  Infection   (See  Abscess)  410 

Treatment    of 272,  399,  462,  464 

Pericemental    Abscess 195 

Pericemtitis,    Chronic 184 

Perspective    142,  144,  298 

Phase     319 

Phenol-Sulphonic    Acid,    Treatment 

with  •••  465 

Photograph   of  Abscess 373,  379 

Photographic  Paraphernalia  Needed, 

Photographic  Prints, 

83,  84,  137,  138,  353 

Physical    Condition 400 

Physician, 

Advice  to 500 

His   position 463 

Placing  Film  Outside  the  Mouth...  349 

Planted  Teeth • 212 

Plastic    Radiography 317 

Plastic  Stereoradiographs 318 

Plate    Changers 300 

Plates  and  Films, 
Advantages  of  Large  Plate  Neg- 
ative . 135,  392 

Fogged    352 

Photographic   Ob 

X-ray  66,     96 

Potassium  and   Sodium,  Treatment 

with    477 

Pose  for  Making  Radiographs, 
Of  the  Antra  of  Highmore.  .117,  341 

"     Of  the  Ethmoid  Cells 341 

Of  the  Lower  Anterior  Teeth 112 

Of  the  Lower  Molar  and  Bicuspid 

Region    108,  110 

Of  the  Upper  Anterior  Teeth 103 

Of  the  Upper  Molar  and  Bicuspid 

Region    98 

Of  the   Sphenoids 341 

With  the  Film  Outside  the  Mouth.  349 
Position  of  Film  and  Direction  of 

X-rays   347 

Position  of  Film  in  the  Mouth.. 94,     95 

Positive  Wire,  Test  for 19 

Positives    83 

Potential    2,      3 

Pregnancy    277 

Preparation  of  Canals  for  Filling.  .  474 
Prescription    447 


Primary, 

Current   11,  27,     33 

Teeth    (See  Deciduous  Teeth). 

Winding    11,  27,     33 

Prints,   Photographic    137 

Development   of 83 

Drying   of 84,  353 

Exposure    83,  138 

Fixing  of 84 

Washing  of 84 

Probing 199 

Process,    Coronoid Fig.  406 

Proprietary  Canal  Filling  Materials.  401 

Protection  287 

Apron    286 

Box   297,  346 

Cabinets  280,  426 

Gloves    286 

Of  Films 297,  346,  350 

Points  in  for  Operator 287,  427 

Screens    .....280,  296 

Shield   59,  285 

Spectacles   286 

X-ray   Tube 285 

Psychoses    256 

Public   Education 441 

Publicity    445 

Pulp    (See  Dental   Pulp). 

Pulpitis    421 

Pulp  Stones  179,  384 

Pulp,  Test  for  Vitality 394 

Punctured   X-ray   Tube 52 

Purchasing   a   Radiographic   Outfit.   292 

Pyorrhea    Alveolaris 193,  464 

"  Pyro  "    76 

Radiodontia    85 

Radiographers,  Advice  to 501 

Radiographic     Appearance     of 

Anterior  Palatine  Foramen ....   364 

Antra   235 

Canal    Fillings 401,  408 

Canal  Fillings  Short  of  Apex. 369,  438 

Cancellous  Spots  in  Bone Fig.  401 

Carious    Cavity 420 

Coronoid    Process    of    Mandible, 

Fig.  406 

Cyst 220  to  225 

Disto-buccal  Root  of  Upper  Mo- 
lars     391 

Fistulous    Tract 199 

Granuloma   (same  as  Abscess). 

Hyoid  Bone   368 

Inferior   Dental  Canal 365 

Mental   Foramen 363 

Nasal   Cavity 365 

Nostrils    Fig.  403 

Odontoma    ._ 152,  228,  229 

Osteosclerosis    382 

Pyorrhea    193 

Spinal    Column 368 

vi 


Radiographic   Outfit,   Purchasing  a.  .292 

Radiograph  or  Radiogram 65 

Radiographs, 

Extra-oral    94,  349 

Intra-oral    94 

Interpretation    of 136,  357 

Made     Direct     on     Photographic 

Paper 347 

Mistakes   in   Interpretation 361 

Preparation   of,     for    Study  with 

Stereoscope  ^ 311 

Technic   for   Making 85,341 

Treatment  Guided  by 413 

Radiography, 

Dental 85  to    319 

Elementary 1   to     85 

Plastic 317 

Stereoscopic   298  to  319 

Radiography  of. 

Canal   Fillings 369,  401 

Canal    Filling   Materials 401 

Cements    403 

Lower   Anterior   Teeth 112 

Lower  Posterior  Teeth 108,  110 

Molars    99,  108,  386,  390 

Sinuses    341 

Upper  Anterior  Teeth 103 

Upper  Posterior  Teeth 98 

Radiolucent 407 

Radiolucency  407 

Radiopaque    407 

Radiopacity    407 

Radioparent    407 

Radioparency    407 

Radiomounts    130,  131,  132,  133 

Radium    Rays 291 

Reading    Glass 393 

Reading    Radiographs    (See    Inter- 
pretation of  Radiograph). 
Records, 
Of  Densities  in  Radiographs.  136,  138 

Radiographic  Records 268 

Rectifier    24 

Reducer 81 

Regeneration  of  Bone, 

203,  381,  400,  465 

Reproductions .   137 

Requirements     of     a     Radiographic 

Outfit  295 

Research  Work 263 

Resection, 

Of   Inferior  Dental   Nerve 252 

Of    Mandible 247 

Of  Tooth  Roots    (See  Root  Re- 
section) . 

Resorption  of  Teeth 157,  165 

Retained   Deciduous   Teeth 157 

Rheostat    25 

Rigg's  Disease    (See  Pyorrhea  Al- 

veolaris). 
Roentgen, 
Ray  (See  X-ray). 


\Vm.     Conrad 49 

Words  (Also  See  the  Preface)  . .     49 

Root  End,  Encapsulation  of 446 

Root  Resection   (Apicoectomy), 

A    Case 468 

Necessity  of   Radiographs 419 

When    Indicated 412,  419 

Roots  of  Teeth, 
Absorption  of   (See  Resorption), 

Amputation    of 201,  413,  419,  468 

Artificial     213 

Forming    160 

Fracture    of 208 

In    Antrum 238 

Radiographed    for    Bridgework. .  209 

Rosin    Solution 485,  486 

Rotary    Converter 36 

Ruhmkorff  Coil  (See  Induction  Coil). 

Salivation 350 

Secondary, 

Current     ....11,  27,     33 

Dentin    .....180,  442 

Rays     57,  63,  289 

Winding 11,  27,    33 

Shield  for  X-ray  Tube    (See  Pro- 
tection  Shield). 

Short    Circuit 19 

Short    Teeth 380 

Shunt     42 

Sinus,  Pus    (See  Abscess). 

Sinuses,    Cranial 341 

Sinuses,    Radiography   of 341 

Skiagraph,    or    Skiagram.. 65 

Slides,    Lantern 354 

Slogan 444 

Sneezing    •  422 

Sodium  and  Potassium,  Treatment 

with    477 

Soft    Tube    Technic 349 

South  Pole  of  Magnet, 6 

Spark   Gap, 
Current  or  Coil  Regulating. .  .35,    36 

Inverse    52,  53,     56 

Parallel    (Same  as  Terminal). 

Series    52,     53 

Terminal     20,  35.  36,  39,  43,  44 

Tube   Regulating 45,  49,  33C 

Spasm,    Facial    Muscles 260 

Specialists   in   Radiographic   Work, 

292,  294 

Spectacles     286 

Sphenoid    Cells 341 

Spinal   Column 368 

Squeegee    Board 3o3 

Stands,  X-ray  Tube.... 59,  60,  284,  296 

Static    Machine 14 

Stereoradiographs, 

Plastic     317 

Technic   for   Making 303 

Stereoscope    298,  299 


Stereoscopic, 

Radiography  144,  298 

Table     301 

Tube    Stand 301,  303 

Sterility 277 

Sterilization,    Technic   of 471 

Stones, 

Pulp    ..179,  384 

Salivary    217 

Supernumerary  Teeth 167 

Suppuration      (See     Abscess     and 
Pyorrhea) . 

Switches     17,  427 

Synchronous    39 

Systemic    Disease 416 

Tables   (See  Charts). 

Target  .; 41,  42,  333 

Distance  of  Skin  to 424 

Technic,  ■■ 

Callahan   for   Canal   Filling.  .474,  485 
Dark  Room  Pointers.  .135,  350  to  354 

For   Covering    Films 97 

For   Culture   Making 472 

For    Developing 74,  128 

For    Drying    Negatives    Immedi- 
ately        132 

For  Holding   Film 109 

For    Ionization 469,  470 

For  Lighting  X-ray  tube. 

89,  91,  93,    94 
For    Making    Crown    on    Tooth 

with   Vital    Pulp 495 

For  Making  Dental  Radiographs, 

85  to  136,  341  to  357 
For     Making     Dental     Negatives 

for   Immediate   Use 132 

For    Making    Electric    Test    for 

Pulp    Vitality 394,  395' 

For  Making  House  Crown 495 

For  Making  Lantern  Slides 354 

For   Making   Negatives 74,  128 

For  Making  Plastic  Radiographs  317 
For  Making  Photographic  Prints, 

83,  353 
For  Making  Radiographs.  .  .65  to  85 
For      Making      Radiographs      of 

Sinuses    341 

For  Making  Stereoradiographs. .  298 

For   Sterilization 471 

For  Using  Coolidge  Tube 334 

For  Using  High  Frequency   Coil     90 

For   Using   Induction    Coil 86 

For  Using  Interrupterless  Coil..     92 

Mistakes  in  Pulp  Canal 458 

Pointers   in 135,  345  to  356 

Pulp    Canal    Surgery 474,485 

Soft   Tube 349 

Van    Woert 132,  134 

Teeth, 
Abscess  of  (See  Abscess). 
Absorption  of    (See  Resorption). 


Anomalies    230 

Canals  of.  (See  Canals). 

Caries    of.    Hidden 269 

Crowned   181,  191 

Cutting  Delayed 148 

Deciduous    ....151,  157,   161,   162,  163 

Delayed    Eruption 148 

Development  of 263 

Differentiation   Between   Primary 

and   Secondary 161 

Enlarging  Canals  of, 

176,  210,  460,  474 

Eruption   of.    Delayed 148 

Extraction    of 162,  168,  415,  464 

Filling  (See  Canal  Filling)  .  .181,  378 

For    Bridgework 209,  495 

Forming  Roots   of 160 

Fracture     208 

Impacted    168,  206,  259,  262,  417 

Lame    184 

Malformed     230 

Missing    14g,  151,  156,  157,  166 

Moving 163,  164 

Planted    212 

Primary  (See  Deciduous). 

Resorption    of 157,  165 

Retained    Deciduous"  Teeth. .   157 

Roots  of    (see  Roots). 

Short     380 

Supernumerary     167 

Tumor    of 214 

Unerupted,     Brought    into     Posi- 
tion     165,  418 

What  Is   Straight  Through.  .Fig.  389 

Temporary  Teeth    (See   Deciduous 
Teeth). 

Tempo  ro-Mandibular    Articulation, 

242,  266 

Terminal  Spark  Gap, 

20,  35,  36,  39,  43,    44 

Tesla    Coil    (See    High    Frequency 
Coil). 

Test, 

For  Polarity  of  Induction  Coil..     41 
For  Polarity  of  Lead  Wires  on 

D.    C 19 

For    Pulp    Vitality 394 

Therapeutic  Agent,  X-ray  as 294 

Thinking,  Where  It  Leads  Us 441 

Third  Molars   (See  Molars). 

Tic   Douloureux    (See   Neuralgia). 

Tic,   Facial    Gesticulatory 260 

Titubator   78 

Tract,    Fistulous 199 

Transformer     (See    also     Interrup- 
terless   Coil) 11 

Trayrocker    78 

Trays   for  Developing    and    Fixing 

74,  350 

Treatment, 

Guided  by  Radiographs 413 

Of   Infection 399,  400,  465 


Treatment  with, 

lodin    466 

Ionization  469,  470 

Phenol-Sulphonic    Acid 465 

Resection 201,    413,    419,  468 

Sodium  and   Potassium 477 

Trigeminal     Neuralgia     (See     Neu- 
ralgia). 

Tube,   Valve 54 

Tube,   X-ray 41 

and     Patient,     Distance     Between 

96,  424 

Bi-anodal    44 

Color  of. 51,  52,  326,  332 

Combination    ZiJ 

Coolidge    331 

Crooke's   41 

Hard 42 

High 42 

High-Frequency   57,     58 

Hydrogen   340 

•    Inverse    in 53,     90 

Low 42 

Properly   Lighted 50,     51 

Puncture  of 52 

Rack 58 

Shield   59,  285 

Soft 42 

Stand   59,  63,  2S4,  296 

Vacuum    41,     42 

Vacuum  Regulator .45,  331 

Vacuum  to  Buy 340 

Tumor 214,  224  to  229,  250 

Turbinate    Bones 237 

Twitching 260 

Unerupted  Teeth, 

Brought    into    Position 165,  418 

Malposed  206,  259,  262,  417 

Unit 326 

Upper  Anterior  Teeth,  Radiography 

of   103 

Upper     Posterior     Teeth,     Radiog- 
raphy   of 98 

Uses    of    the    Radiograph     in     Den- 
tistry   146  to  273,  416  to  423 

Using   Coolidge   Tube,    Technic...  334 


Vacuum    41,    42 

Regulator    45,  331 

X-ray  Tube,  of 42,  340 

Valve    Tube 53,  337 

Van  Woert, 

Developing   Tank 134 

Film  Holder  and  Indicator 350 

Technic    134 

Velocity  of  Electricity 3 

Velox   83 

Ventilation   of   Dark   Room 348 

Vibrator 17,     23 

View    Boxes 136,  406 

Villard   Tube 54 

Volt    :......       3 

Washing, 

Of    Negative .79,    132,  350 

Of   Print 84 

Watt_ 5 

Winding, 

Primary    11,  12,  27,     Zi 

Secondary 11,  12,  27,     2i2) 

Wiring    for   Installation 15,     Z6 

Wires  in  Canals.  173  to  176,  179,  183,  ?,77 
Wisdom  Teeth   (See  Third  Molars) 

X-ray, 

As   a   Therapeutic   Agent 294 

Burn .273,  274,  290,  425 

Carelessness    with 426 

Dangers    of 273 

Dental    Machines 320 

Discovery   of 49 

Dose    of 288,  424 

Film 66,    96 

Ignorance   with 426 

Limit   of    Exposure   to 288,424 

Machines    14 

Outfit 295 

Penetration   of 56 

Proof    Box 297,  346 

Tubes    (See  Tubes). 

Tube    Stand 59,  60,   284,296 

Unit    .....326 


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